Artificial Brilliance

Artificial Intelligence. The golden dream of both game designers trying to make the next Killer App, and megalomaniacs attempting to build a viable Robot Army to Take Over the World.

Artificial Brilliance is, quite simply, the ability of the computer characters to make the player think "Hey, these guys are actually pretty smart!" It occurs when the A.I.'s freeform actions, based on real-time decisions, result in behavior that seems, frankly, brilliant. It can be anything from an enemy that manages to outwit and outmanuever the player on the player's own terms and by the player's own rules, to an NPC ally who manages to assist and even save the player in ways that are unexpectedly helpful and seemingly smart. Just being able to react quickly and enter button combinations flawlessly doesn't count, computers are naturally good at that; in fact, toning down a computer player's inhuman speed can be a facet of Artificial Brilliance.

The polar opposite of Artificial Stupidity, when the A.I. makes unbelievably bad decisions that make the player think it's a complete moron. That doesn't mean Artificial Brilliance and Artificial Stupidity can't overlap, however. No A.I. is perfect, and glaring imperfections and mistakes can be all the more obvious in a game with A.I. that is generally impressively smart.

Of course, it's a balancing act between an AI that is bad at the game and an AI that is too good at the game. The trick is allowing the AI to make human like mistakes while also allowing it to make human like brilliance. After all, in a first person shooter, the AI isn't really playing the game in the same way a human does. They don't actually have a mouse/keyboard to manipulate or have to watch a monitor. Thus it's an easy task to make an AI that always knows where you are and can hit you perfectly; it's not so easy to make an AI that can act like it doesn't know where you are and can act like it has reflexes. And as some of the examples below note (see the Half-Life example about greatest threat), sometimes being smart makes it dumb.

Some games avert the issue by explicitly making the computer play a completely different game thus negating the need for the AI to present the illusion of competence equal to the player. For more discussion on AI's, see Video Game AI.

Game Shows

 * Most recently, IBM took another shot at human vs. computer, with Watson starring on Jeopardy!. The machine can answer the questions almost as well as a good human player, and (more importantly) its perfect timing on the buzzer gives it a nigh-unbeatable advantage. It beat the two highest-ranked human champions by a three-to-one margin.
 * In doing so, however, Watson exposed the limits of his brilliance more than once, giving wrong answers that no human would guess.
 * In an instantly classic moment, a Final Jeopardy! question in the category of "U.S. Airports" wanted to know the city with two airports, one named after a World War II hero and one named after a World War II battle. The answer was Chicago, but Watson answered with "What is Toronto?", prompting much hilarity about how apparently Toronto had been annexed with nobody noticing. This was caused by a slight oversight in Watson's programming that intentionally undervalued the category name since the category doesn't always have much to do with finding the answer. Since the clue didn't mention a country, Watson didn't rule Canadian cities out of its answer. In addition, according to the developers it didn't really understand the question (it didn't get the connection between World War II and airports)... so it guessed.
 * In the "Literary APB" category, the clue wanted to know the person responsible for the murder of Severus Snape -- "he'd be easier to find if we could just name him!" Watson didn't know and didn't buzz in. His top three choices were Harry Potter, Albus Dumbledore, and Voldemort. Watson had very obviously figured out that the answer had something to do with the Harry Potter franchise, but didn't understand that the category was exclusively villains (being unable to make the link that APBs are only issued for criminals), and couldn't catch the allusion to He-Who-Must-Not-Be-Named.
 * In Shocking Swerve, Watson was defeated shortly thereafter... by a Congressman. Rep. Holt (D-NJ) to be precise.

Board Game

 * Computers have gotten really, really good at chess.
 * They haven't gotten quite as good at Go, but the average beginner will still lose most or all of their first 50 games against it.

4X

 * Galactic Civilizations is known for this. See especially this After Action Report, which goes so far as to cause Artificial Fridge Brilliance. In the mid-to-end-game, the player was up against an alliance of a warmonger, a diplomat and an average race. The warmonger could have crushed him easily, but didn't. In fact, he even used his massive empire's voting power to punch through a galactic motion for peace against all three other races. The reason for this uncharacteristic behaviour: If the player had been defeated, it would have instantly resulted in an Alliance Victory, meaning a victory primary for the diplomat race that engineered the alliance. The goal of the warmonger faction was to keep the player alive until it was strong enough to break from the alliance and conquer both of its former partners at once - and the diplomat even anticipated this betrayal and built up his forces explicitly to be strong against his own ally. At which point the player happened to play "lucky third party" by achieving a Technological Victory.
 * And if Word of God is to be believed, this is another one of those things where the AI was never intended to do anything even close to what happened.
 * Back in the first Galciv, one of the people who wrote the A.I. was repeatedly curbstomped by his own creation.
 * It's telling that the "Normal" difficulty setting has the AI's economy working at reduced power, with the mechanically equal setting known as "Tough".
 * Galciv's spiritual predecessor, Master of Orion, also has some very clever AI. The Impossible difficulty really earns its name.
 * Sword of the Stars AI can recognise your weapon loadouts and adapt by using the appropriate counters.
 * The battle AI leaves something to be desired, though. Enemy ships armed with only ballistic and missile weapons will keep hammering away at your deflectors, which cover only the front of your ship, even though they have no chance in hell at penetrating the shield, instead of flanking. Ditto for energy-armed enemies against disruptors. In fact, the battles pretty much boil down to "get close to the enemy and keep firing until either side is dead". Retreat is not an option, unless the ship in question is not a strict military vessel.
 * The AI will also never explicitly target your ships' turrets or specific sections. It'll fire at whatever's closest. This gives the player doing this an advantage.

Card Game

 * Older Yu-Gi-Oh! games relied on psychic AI and other gimmicks to provide any difficulty, as otherwise the AI was very poor. In Stardust Accelerator and Reverse of Arcadia, however, the AI actually takes time to consider the possibility of every possible move and the consequences in order to decide the best action. The AI will take note of things such as what cards will provide better advantage, whether they can subvert the Tribute process for certain cards and monsters, and which ways they can take control of the situation, to name a few.
 * For Wizard of the Coast's Magic: The Gathering video game Duel of the Planeswalkers the programmers had a very difficult task in programming an AI that could deal with all the rule-changing cards of the game itself (and there are possibly more of them than in any other cardgame because of Magics "Golden Rule", which states that the text of a card takes priority before the rules themselve). Seemingly they succeeded.
 * This refers mostly to the second game by that name and publisher. While the first game's AI was a remarkable achievement for its time, there was no way to provide it with hints on how to play specific decks, rendering a number of monsters crippled in the single-player game (their difficulty was instead balanced though life handicapping and chance of AI Roulette). (It also tended to cast any playable spell as soon as possible, and assume you have no castable spells, a greater weakness given the longer games 5th Edition tended towards.)
 * Poker Night At the Inventory uses an AI system that not only considers each character's hand, but also factors this in with each character's unique personality and abilities. Thus Tycho and the Heavy will play cautiously and strategically, Strong Bad will usually attempt an overconfident bluff, and Max will play erratically to reflect his short attention span and poor grasp on the rules of the game (and possibly use his future vision power to cheat. Yes, this game even applies that trope in a justified manner.)

Fighting Game

 * Many fans of Super Smash Bros Brawl have argued that the level 9 AI is capable of learning from human players. Players often point to examples of a certain characters' AI altering their recovery strategy after a human player has repeatedly used this character. Though this has been proven false but the rumor still persists.
 * The stock AI can also be replaced with more effective AI. Among various projects, one Japanese hacker is working on an Ice Climber AI that never messes up its chaingrab infinites, something that is possible for humans—ie. not a true example of cheating AI—but difficult.
 * A similar rumor exists for Samurai Shodown 5. The AI on higher difficulties will alter tactics in response to the player.
 * Sonic Battle: If you just spam a special attack to beat an opponent and they respawn, they'll change the special moves they use- since each player is granted immunity to the type of special attack they aren't using to attack, spamming one type of attack will lead the opponent to swap specials to defend against yours. This also runs in reverse, with the computers changing their specials to get by your immunity.
 * The AI in Fate Unlimited Codes tends to come in two flavors: dumber than a rock, and smart as a human. On harder settings, the difficulty in fighting the computer lies in how they use human tactics, particularly mixups leading into absurdly long (but entirely possible to emulate) combos.
 * Captain Cadaver, a boss in Maximo seems to be just another circular-arena projectile-flinger, but unlike most bosses, he actually calculates where you will be by the time the shot reaches you by measuring how fast you're running. Instead of running in circles like most games, you now must run away in strategic patterns. How unexpected!

First-Person Shooter

 * The first fan-made "bots" for Quake were a major leap in terms of A.I., being able to imitate the movements and behavior of a player-like character (as opposed to the simplistic "move in a straight line and shoot" enemies of the time).
 * Unreal was the first FPS game to use "bot-like" A.I. for its single player enemies, leading to the creation of the memorable Skaarj, a video game adversary that could dodge and strafe while firing, jump from platform to platform, intelligently pursue the player throughout the entire level, and otherwise move and behave just like the player character instead of (as was the norm at the time) a simple turret-like enemy wandering aimlessly in semi-random directions while periodically pausing to fire at the player's direction.
 * Skaarj would sometimes even retreat, only to lead you into an ambush if you gave chase.
 * Half Life is famous for introducing the first "tactically intelligent" A.I. enemies in the form of the HECU Marines. These soldiers operated in squads, provided each other with covering fire, would toss grenades to flush out or kill the player character, and would navigate between obstacles and circle through the level in an attempt to outmanuever the player instead of simply charging suicidally at him in a straight line.
 * The A.I. of the Combine soldiers in Half Life 2 has been widely criticized for being rather average, uninteresting, and easy to kill. In fact, the Combine A.I. are actually quite impressive, demonstrating such feats as moving in squads, "slicing the pie" around corners, using cover intelligently based on their relative position to the enemy, stacking up, providing and advancing under covering fire, flanking, and using pincer attacks. Unfortunately, they're not really as mobile as they could be, and the tight, linear corridor level design never really gives them a good chance to show off their moves (that, and the fact they die like lemmings because Gordon Freeman is a walking tank that runs like an Olympic sprinter). This youtube video gives a pretty good representation of the actual capacity of the game's A.I.
 * Valve specifically searched the Quake Mod community (mentioned above) to see who was designing the best bot AI, and hired them.
 * Also, even in the linear setting of most of Half-Life 2 the AI does sometimes pull off something clever. Like those horrible times you're cowering from the hail of SMG and pulse rounds, only to see the red streak from that little light on the top of a grenade arc towards you...
 * Also, the Combine gunship, which were programmed to shoot at "the greatest threat". It exceeded the dev team's expectations by shooting down incoming missiles, rather than at the player.
 * Leading to the sad case of Artificial Stupidity in which they would never fire at the player as long as a (smarter AND faster) missile was in the air. Any number of gunships could easily be defeated at no risk as long as the player could keep a missile flying in circles until it could hit one from behind, then launch another or find cover immediately. Partially averted
 * Raven Software is well known for pioneering the use of friendly NPC A.I. squads in FPS games, beginning in Star Trek Elite Force and continuing on in Soldier of Fortune 2 and Quake IV. Their games often feature friendly A.I. squads of several NPCs who are capable of following the player throughout an entire level and also of holding their own in firefights against waves of enemy NPCs. Notably, they make generous use of Gameplay Ally Immortality to avert the frustration that made Daikatana the smoldering pile of ruin it is remembered as.
 * The friendly A.I.'s ability to follow the player in most Raven games without getting lost or stuck is usually due to the use of strictly linear No Sidepaths, No Exploration, No Freedom levels, but it's still impressive given the time it was made.
 * F.E.A.R. was widely praised for the A.I. of its Replica Soldiers, touted as the best enemy A.I. ever at the time of its release. Enemies would work in squads, provide covering fire for each other, advance under covering fire, fire from behind cover intelligently, and even use cover to flank and circle around the player instead of charging straight for him and making themselves an open target in the process. The A.I. also had extremely high mobility allowing it to exploit the entire battlefield instead of limiting itself to a single small area, and could also dive through windows, vault over objects, and crawl under obstacles, allowing it to access every area of the level the player could.
 * The F.E.A.R. A.I. is actually a good example of emergent behavior, which is programmer-speak for "we didn't program it specifically to do that, but for some random reason it does it anyway, and it's really, really cool that it does!". More accurately, complex behavior stemming from simple rules. Specifically, the A.I. is programmed for a limited number of simple behaviors: moving in coordinated squads, providing covering fire, seeking cover, and repositioning itself based on the player's movement and position. The A.I. isn't actually programmed to flank or circle behind the player, but its tendency to seek cover and reposition itself based on the player's movements results in flanking and circling behaviors occurring naturally without "conscious" effort on the A.I.'s part (mostly due to the A.I.'s high mobility combined with its preference for seeking lateral cover rather than charging the player directly).
 * Also of note is that of the level design. The levels were designed to help facilitate the AI in action. You will find that there's generally two ways to get to any position thus always allowing the AI to find a path. Of course, this also gives the player the impression that levels are bigger than they are so it was a win-win.
 * STALKER: Shadow of Chernobyl features a complex Artificial Life ecosystem featuring both wildlife and human NPCs. It has an ecosystem of monsters that live in packs, defend their territory, and even migrate from area to area. It also features human NPCs that live out their own lives independent of the player's actions; exploring the Zone, traveling from map to map, resting at friendly camps between forays through hostile territory, scavenging loot, and getting into fights with other NPCs and monsters. Tactically, the combat A.I. in STALKER is pretty damn good too. Enemies flank, use cover, retreat, dodge behind and through obstacles and buildings, and are pretty good at navigating the game's wide-open levels. The A.I.'s Achilles Heel is its inability to recognize environmental hazards, causing NPCs to blithely walk through Anomalies, resulting in their instant death by crushing/eruption/electrocution/etc. If the press on the pre-release preview versions is to be believed, the AI was even perfectly capable of beating the game itself. It's perfectly understandable on why the developers disabled that for the released game, though.
 * The enemy AI for the Legendary difficulty level in the Halo games is notoriously brutal, but still holds back in order to provide a reasonably playable game. One of the easter-egg Skulls in Halo 2 (named "Whuppopotamus" in the game files) corrects this, allowing enemies to discern the wibbly outline of a cloaked foe, hear guns reloading, and generally behave as though they were capable human players. Meep.
 * Exacerbated by the Artificial Stupidity of the friendly AI.
 * Halo: Reach's Legendary veered into The Computer Is a Cheating Bastard, with things like Covenant turrets firing faster and with more range and accuracy than the player can when on them, and enemies that track and home in on the player the second he sticks his nose out, especially when the shields are down.
 * With some recent patches and updates in Left 4 Dead, the special infected have become a little smarter when it comes to attacking the survivors and dealing with fire. Boomers and Hunters will usually wait around a corner and then strike once someone is in their range. If a survivor is close enough, the Boomer and Hunter will usually attack by slashing rather than vomit or pounce them. Tanks are also smarter when it comes to fire; if there is a way around the fire, the Tank will usually go around the inferno.
 * Left 4 Dead 2 upgrades the Tank's intelligence. In the first game, if the Tank knocks someone down, it would stand over the survivor and pound the hell out of them while the other guys blasted it to death. The sequel now changes the Tank's behavior where after it knocks down someone, it will usually ignore the downed survivor and run after the other survivors, just like what someone would do if they controlled the Tank in VS mode. All the other special infected have also smartened up where now they will tag team you if given the chance. Additionally, if a player throws a molotov, hunter bots will light themselves on fire intentionally, then pounce, dealing extra damage; and smoker bots will try to drag players through the flames.
 * Jockey AI is also frighteningly intelligent when it comes to forcing survivors through a hazard. Is there a Spitter acid nearby? The Jockey will actively try to steer you into it (and ditto for any fires started by survivors). Is there a Witch nearby? The Jockey will gleefully steer you into her for a one hit knockdown.
 * Turok 2: Seeds of Evil had the Endtrail enemy, which use cover whenever possible, move around to make itself harder to target, chase you a bit and use hit & run tactics. The other enemies of the game weren't so bright, however.
 * The AI for the offline mode for Team Fortress 2 has its periods of fail from time to time, but at least it knows that when on defense, spam Soldiers and Demomen.
 * The Bot AI has gotten remarkably better in recent months. Engineers will check suspicious behavior around their buildings, and snipers will now be smart enough to back off while firing their SMG instead of charging enemies. If spies are spotted, expect a thorough round of spychecking from the bots. Medics will also wait until their patient is incurring damage to engage an ubercharge, and scouts will know to use their pistols to take out sentry guns outside their effective range. Bot pyros are also quite good with using the airblast secondary attack on their flamethrowers to clear points and reflect projectiles.
 * Star Wars: Republic Commando was notable for having exceedingly good party AI. If you told one to take up a sniping position, they would get there unless there was a positively absurd amount of stuff in their way and no intermediate cover, and would last quite long in such a position without assistance. If you got shot down (which at times happened frequently), your team would either cover each other as they attempted to heal you, or set up a proper defense and wait out the threat depending on your orders.
 * The AI was massively improved in Halo: Reach. Apparently, they were programmed to behave like real players. When a grenade falls near them, they will engage Armor Lock if they have it. They'll take cover, dive away from bullets, and basically play like you would.
 * The Stalker from Dead Space 2 is designed to behave similarly to the velociraptors from Jurassic Park, meaning they will attempt to flank the player while another peeks around cover within your field of view in order to distract you. They can be very effective.
 * The first time you play BioShock (series) you will be amazed at how eerily realistic the splicers act.
 * Crysis and Crysis 2 may have their occasional hiccups, but the enemy AI in both games shows impressive levels of intelligence. Enemies will suppress you and flank your position, call in re-enforcements and sweep the area for you if you try to hide. In Crysis 2, a highly alert enemy will notice a cloaked player if they are close enough (though by then, it is typically too late) and they will throw grenades at your last known position, or where they think you may have gone. Enemy troops will even track what direction you're going in; if you run toward cover while the enemy can see you, cloak, and then change direction, the enemy will continue firing along your original path and try to suppress the general area it thinks you were running toward.
 * Command & Conquer Renegade does not have the most stellar AI for most of the normal troops you fight. However, stealth troopers have actually been observed stalking the player and ambushing when you least expect it. Also, Nod troops who do not have any other valid targets in sight will immediately shift their attention to any abandoned but operational GDI vehicles they can find to deny them to the player.

Flight Simulation Game

 * While Ace Combat's AI isn't known to be the smartest, more recent games have demonstrated better AI abilities, such as better response from teammates to orders (Pixy (ACZ), for example, behaves much better than the rest of Wardog Sq (AC 5). combined, to say nothing of Shamrock (AC 6)). A very good example of better enemy AI is in Zero, where Ace Pilot squadrons that come in several missions will constantly flank you and keep your wingman busy while they move in for the kill. They move so well-coordinated that one reviewer notes that "They put the Yellow Squadron (of Ace Combat 04) to shame."
 * Notably, the Ace squadrons almost always outnumber you 2 to 1, and they use their numbers to their advantage. One plane might act as bait while another tries to shoot you down, and in particularly annoying furballs, three planes will come after you while the fourth keeps your wingman busy. The one squadron that doesn't outnumber you (Gelb, which only has two planes, as do you) is in vastly superior planes to what you're normally flying at that point in the game.

Maze Game

 * Pac-Man is perhaps the earliest example of "smart" A.I. in a video game, as each of the four ghosts was programmed with a specific "personality" and navigating/tracking style that allowed them to make decisions on how to pursue the player character, rather than simply moving at random or in a linear line. The aggressive Blinky was programmed to chase Pac-Man, the cunning Pinky was programmed to corner Pac-Man (by heading toward a spot a few steps ahead of him), the wired Inky was programmed to follow Blinky and try to aid, and the scared-witted Clyde was programmed to run away when he got close to Pac-Man. Ms. Pac-Man made the ghosts move randomly for the first 7 seconds so that players couldn't learn and re-use an optimal path. More here.

Mecha Game

 * AI behavior in Armored Core isn't the best, granted, but in Silent Line, you are able to train an AI pilot of your own. The AI starts out very stupidly, but as you pilot the AI's assigned mech, the AI starts emulating your combat behavior, both good and bad. With enough practice, the AI would even be able to accurately aim rockets, something that even the best human players have difficulty to do. The AI opponents in the Arena also improve with repeated combat exposure.

Racing Games

 * In Mario Kart DS, the AI actually seems to know that if you put a banana peel on the loop-the-loop, Hilarity Ensues.
 * Mario Kart 7 upgrades the AI's tactics with items. Now they will usually drag items behind them for a while (shells, banana peels, etc.) before using them so that players can't make them crash with their own items too easily. Should you get in the line of sight of an AI racer? They won't hesitate to use their items on you.

MMORPGs

 * World of Warcraft generally has fairly limited AI opponents with only a handful of abilities. The encounter commonly referred to as Faction Champions in the Argent Coliseum, however, is quite impressive - it's meant to mimic a huge PvP battle, as each enemy has access to most of the spells you'd expect a player of the same class and specialization to use, the healers are quick to remove status effects and heal injured comrades, and the group will often gang up on one player and then switch to a completely different one.
 * And before the Argent Coliseum, we had Princess Delrissa's party in Magister's Terrace, and the Tier 0.5 arena battle in Blackrock Depths.
 * Guild Wars still does have some obvious flaws with the AI, namely that they'll attack enemies rather than trying to run away from them, and that the heroes often need you to tell them how to use the more complex builds, but the specs they do have, they know how to use. It also helps that if you ping a target, they immediately focus fire whereas all that does to players is say "Attack here".
 * Still even some individual behaviours are nice - Herta uses the Ebon Hawk-Stoning combo, the interrupt/domination henchmen are actually really good at interrupting (helps they have godlike reflexes), Minion Master heroes will actually heal their minions if you have them use something like Karei's Healing Circle or Heal Area, etc.
 * EVE Online has introduced an AI package called the "Sleeper AI" in March, 2009, which is specifically designed to allow special "Sleeper" NPC ships to combat player ships toe to toe at similar numbers and ship classes. NPC ships with Sleeper AI execute agile maneuvers to avoid turret fire, remotely repair friendly ships that are the most damaged (a practice called "Spider Tanking"), and most importantly, switch targets according to the threat level of each enemy ship at semi-random intervals. The threat level is calculated dynamically based on the target's firepower, total hit points, repairing capabilities and special abilities such as electronic warfare or remote repairing capabilities. The end result is a group of NPC foes that can emulate human behaviors in fleet warfare and blowing up unprepared foes into smithereens, and such foes take a lot more preparation to defeat than mooks without Sleeper AI. Fortunately, the use of Sleeper AI is resource intensive to the server, so regular NPC Pirates("Rats") are still nothing better than piñatas.
 * A refined version of Sleeper AI package is currently being used by the Sansha's Nation incursion fleets, and is introduced in the eponymous "Incursion" expansion in Jan. 2011. On top of the features provided by the Sleeper AI, the Sansha's incursion ships are equipped with specialized behavioral rules base on ship classes and roles (stealth bombers targeting larger ships for torpedoes, electronic warfare ships pinning down smaller support ships, battleships focusing fire on single targets, etc). As many regular combat mission runners severely underestimated the competence of Sansha's incursion fleet and ran into them unprepared, the galaxy map with the "Ships Destroyed within 24 Hours" filter lit up like a christmas tree for more than a month, making the developers, and especially the in-house economist, very, very happy.

Platformers

 * Rock Man 4 Minus Infinity
 * If you use Rush during the Snatchman battle, the doppelganger will use it against you. Yes, you can end up healing the boss when you're low on health! To really rub it in, it still uses your weapon energy.
 * More brilliance: all the Robot Masters change their patterns to dodge Rush Cannon if you fire it at them. Some even turn it against you!

Programming Game

 * Battlecode is a competitive game for programmers in which they must program their own AI for their robots. When the game actually begins, players have no control over the robots; they act based on the player programmed AI.

Puzzle Game

 * One of the most notorious puzzles in The 7th Guest is the Microscope puzzle, where you have to face off against Stauf himself in a game of cellular Reversi. It's already hard enough when Stauf goes after the player, and can screw up any move the player pulls off. What makes this maddening is that Stauf's intelligence is tied to your processor speed, so the faster your processor is, the move moves Stauf can predict, and the harder he'll be to defeat. Back in the days of Windows 3.1, this puzzle may yet have been beatable, but on today's quad-core processors, it's essentially impossible.
 * This is the reason Puzzle Quest has such a notorious reputation for cheating. The computer doesn't make mistakes. It doesn't miss 4 in a rows, and knows how to set them up for optimal follow-ups. Combined with observation bias and some less than perfect playing on the human's part, and it seems to be cheating.

Real Time Strategy

 * AI War: Fleet Command, a seemingly innocuous indie 2D space RTS made by a single person. But that doesn't stop the AI from actually understanding flanking tactics, creating distractions for the human player, utilizing hit and run warfare...
 * Despite how stupid the AI Bots are in League of Legends, there's some Artificial Brilliance in there, too. Players may not be quite aware that if you try to finish off a retreating champion by a turret, it'll stop shooting at Minions and start firing at you. Bots know this, and if a turret ever starts firing on them, most of the time they start hightailing it out of there. If you blind or silence them, they run. Not to mention, the bots will try to goad you into attacking them when they're next to a turret - and if Shen bot is running over to you while you're attacking a turret, the best thing to do is get out, because he will taunt you and cause the turret to start shooting you instead. They know the rules.
 * Ryze, Annie, and Trundle bot go positive. Trundle is able to put his obstacle in the absolute WORST location possible, whereas players will often mess up. Ryze Bot will often harass you with Rune Prison (sometimes right next to a turret), and Annie bot is well aware that her passive gives every fifth spell a stun. You'll notice that she'll sometimes use her Disintegrate to last-hit minions...however there is a visual warning that says her stun is ready. Immediately, she stops last-hitting minions with Disintegrate and starts to go right for you. She even knows the oldest trick in the book when it comes to Annie - saving her stun and using it when she summons Tibbers.
 * The AI in the original Supreme Commander and its expansion Forged Alliance is far from perfect, and in fact often actively cripples its own chances of success, but higher levels are excellent at early-game harassment and have nearly perfect base layout and economy management. The true brilliance, however, is that the Adaptive AI will occasionally emulate player tactics it has observed to be effective, and will use them against the player.

Roguelike

 * This is the point of the short roguelike Smart Kobold. Your character's a nigh-indestructible melee-fighting death machine (i.e. a typical late-game player character) with no ranged attacks, so the second you set foot in their caves, they grab all their weaponry, valuables, and babies, and start running (setting traps as they go) into a large room from which they can easily snipe you to death. If you somehow manage to corner one of their mages or archers, there's a good chance he'll snap his wand or bow in half to deprive you of the ranged attack you'll need to win. Furthermore, even when you do get a ranged attack, they'll do their best to stay at maximum range - or in the "blind spot" between the eight directions you can shoot in, like Nethack's unicorns.

Role-Playing Game

 * In Crisis Core: Final Fantasy VII you will find yourself frustrated by enemies who chain their attacks such that there's almost no time to dodge, or that rolling to dodge one attack leads to Zack entering recovery frames in time for another to land.
 * This is why your party members are useful in Final Fantasy XIII. Synergists remove debuffs and prioritize buffs that are more effective against whatever you're fighting. Ravagers focus on whatever a Commando's doing and try to help him/her out, focusing chain attacks or spamming area-of-effect spells. Saboteurs focus on debuffs the enemy is weak to, remove enemy Status Buffs efficiently, and prioritize based on what everybody else is doing. Medics remove debuffs quickly and select spells based on how injuries are distributed. Synergists prioritize the most helpful buffs for the situation. Sentinels are really effective at drawing and surviving enemy attacks.
 * In addition, they act in the way an actual human will. Against an unfamiliar monster, they will use ineffective elements or debuffs simply to test things out; once they figure out that those moves don't work, they'll switch to something else. Should the player character use Libra, they'll instantly stop doing that and only use moves that will work.
 * It should be noted that this also doubles with Artificial Stupidity, while the feats of brilliance listed above are true, the AI sometimes makes rather questionable decisions using the skills of certain Paradigms. For instance, a Medic controlled by the AI will usually heal with one Cure spell at a time, even when waiting for the full ATB bar to fill and casting 4 cure spells is better, or using Area of Effect spells like Cura. Other times it will heal the Sentinel, who can clearly recieve the damage coming it's way, while the Medic gets pounded by the Area of Effect attacks or enemies in melee range, nevermind that the Sentinel's job is to take damage, or that the Medic is squishy, if the Medic dies he can't keep the Sentinel alive. Most of the times this situation occurs will end up in said AI-controlled Medic dying and the player shifting into Medic in order to properly heal the Sentinel and Revive the fallen.
 * Also, annoying, the AI understands what a good attack element is, but not necessarily what a good attack is. For example, when Sazh switches between a physical attack and a magical attack, it takes almost two seconds to do so. Despite this, the AI will constantly switch between physical and magical attacks. And sometimes, when the enemy has specific elemental weaknesses, the AI will exploit them, and then tack on a non-weakness element for no reason, using fire, fire, fire, and wind, for example.
 * Ravagers' AI do this because linking different attacks boosts stagger more efficiently. Doing fire, flamestrike, fire, flamestrike on an enemy weak to fire adds a 1.4% base increase to the gauge than 4x fire would, for example.
 * Enemies also exhibit this. PSICOM compensates for their lack of sheer power with effective cooperation, and have the annoying tendencies of focusing their fire, buffing each other, and removing your buffs.
 * Some CPU opponents in Pokémon are actually like this when they're not committing suicide or cheating, especially prevalent in the more recent years. They now know what type your Pokemon is, and if it has a weakness, especially a double weakness, they will exploit it just like a player would. (Oh, sending out a Vespiquen on me? Eat Power Gem! Think that Torterra is so hot against my Luxray, huh? It may be immune to Thunder Fang, but it's not immune to Ice Fang!) And some trainers/Pokemon are even smart enough to exploit moves that benefit under a certain environmental condition, which is why Groudon and Kyogre have Solarbeam and Thunder, respectively. And in Generation IV and above, they begun to think about you trying to use the most common weakness - Trying to use Water, Rock, or Ground Pokemon against Flint's Fire Pokemon? Well you better get them down fast, because if you don't, they're going to use the Sunny Day + Solar Beam combo until you cede defeat.
 * In the latest generation, some trainers (especially Ace Trainers and your Rivals) will even set up specific move combos more commonly found in Metagaming competitive circles, like Endeavor-Quick Attack and Mean Look-Curse (Ghost type).
 * Ghetsis' move pool on his Hydreigon would count as this, but surely was designed this way. Instead he uses his AI to oneshot your team with the right type attack.
 * Justified in-story via Fridge Brilliance. He wasn't expecting you to befriend the other Legendary Dragon, wasn't expecting you to stop N, wasn't expecting to have to battle you himself, doesn't know what he's up against, and is freaking out.
 * Not only that, they use smart responses to your moves. For example, they'll stop using attack moves if you start using Bide.
 * The final boss of Lunar Silver Star Harmony is a nightmare because of this. Good luck keeping Jessica alive, because he knows to Shoot the Medic First, for one.
 * Golden Sun: Dark Dawn shows a case of this with the Ancient Devil's Demon Sign. He is capable of judging which of your members is most damaging to him either by pure damage, healing potential or some combination thereof, and control that character, provided they're on the front line and conscious. Also, said character, once controlled, is highly prone to using the party's standby Djinn for summons against you. His number-one target for Demon Sign is Sveta, of course (don't use Beast Form—oh, too late).
 * Xenoblade has a battle system that relies on well-timed, structured combos of special abilities, and often relies on two or even all three party members using skills in concert. The player can only control one at a time, but fortunately, your AI partners are smart. Each has their own AI, uses their skills at the best time and position they can, and tries to fulfill their proper role: for instance, your tank will switch targets to draw aggro away from other characters, while squishier characters will stop using skills for a few seconds to let that happen.
 * The first four games of The Elder Scrolls had AI that was at best laughable, since they would just dead-zone you and try meleeing (if you could tell they're doing that; sometimes the sprites wouldn't show them attacking) or use up all their magicka in the first ten seconds and then stand in front of you swinging their weapons, while saying they fought mudcrabs better than you or calling you an n'wah. However, Skyrim features much better AI. Enemies might flee into another room to get help to fight you, archers will switch to a dagger when they're in melee range of you, and enemy casters are annoying because they'll use frost spells on you to reduce your stamina and deny power-attacks And mages, when fighting other mages, will spam lightning on you to drain your magicka. Oh, and some of the higher-level Draugrs, who're armed with Shouts, will disarm you and force you to pick up your weapon while they get free shots. It's most prevalent to archer-player characters. The enemies know it's harder to hit a moving target, and will sometimes notice you're aming at them and will strafe, sometimes they even wait until after you fired to sidestep and force you to miss. They also know the game averts the No Arc in Archery and will often shoot arrows from seemingly impossible angles where an archer trying to counter-attack would miss due to an object in the way.
 * Players have also reported dragons use PC-tactics against players. They're well aware that sometimes, people will sometimes Gang Up on the Human and land in a spot where you're forced to go into the aggro radius of other monsters who will then weaken you while the dragon breathes on you. Another observed tactic is that a dragon may attack a monster and then fly around the player, causing the creature to follow, approach the player, and attack him/her.
 * NPCs that can cast magic on themselves do so in appropriate contexts. Powerful vampires, for example, are quick to cast invisibility on themselves before running away.
 * Some enemy mages will also use healing spells when their health gets too low, making it nearly impossible to use hit-and-run tactics to wear them down, as you could against a non-mage enemy.
 * Ice Wolves appear to be moderately clever, making a small effort to flank the player rather than charge headfirst into a sword.
 * Just when the player thinks he's gotten away with stealing, zero bounty and all, he may later encounter armed mercenaries sent after him, one of which is carrying a contract that reveals that whoever the player stole from sent them. If the player survives that encounter, the Dark Brotherhood may show up next...
 * Note: Little girls can hire bandits as well. So yes, a 10 year old can hire criminals to kill you.
 * Hostile archers will constantly move back and forth if you're armed with spells or bows. They won't move at all if you're running toward them to attack in melee.
 * Mass Effect 2 has pretty good AI, especially on Insanity level. Enemies "leapfrog" each other, use powers to flush you out, and flank you.
 * Mass Effect 2 has got NOTHING on Mass Effect 3. From the demo alone, the game has displayed ridiculously impressive AI who use their powers and abilities and strength in numbers to overwhelm and flank you at an incredible rate. Its got probably the best tactical AI since F.E.A.R. or Crysis.
 * See the trope page for a bulleted list of brilliant tactics, exhibited by Cerberus units alone.
 * Indie RPG Fortune Summoners features extremely good friendly and enemy AI. Pretty much every enemy in the game up to and including the very first slime you encounter will bob and weave around your strokes and teach you very early on that mashing attack is very much not an option in this game. On the other hand, the meek little Staff Chick you pick up early on will lead you on with her easily-terrified demeanor, then proceed to effortlessly dance right through a cloud of enemies while keeping you healed.
 * Heaven forbid you try Vs. mode. One could be forgiven for thinking your own main character got hijacked by Atlus or something.

Simulation Game

 * Creatures was notable for its use of a genetically coded Artificial Life system, allowing you to breed creatures called Norns, mixing their DNA and resulting in evolving behaviors unpredictable to the original programmers.
 * Unfortunately, there was a lot of variation, especially early on, so this behavior often included things like steadfastly refusing to eat until dead.
 * And Wallbonking.
 * Also, Socrates, a norn genetically engineered to be incapable of learning from experience, actually did better than the normal norns. Their ability to learn isn't as good as their instincts.
 * Black and White is famous for its use of The Creature, a pet that acted as the representation of your power on Earth (since your status as an incorporeal god somewhat limits your ability to affect the world directly). The Creature acts independently and cannot be controlled directly, but can learn and be taught a wide variety of behaviors through a combination of classical conditioning (stroking them after they do something you want them to do, and spanking them after they do something you don't want them to do) and imitative behavior (if your creature sees you setting fire to villagers, he'll start setting fire to villagers). In this manner you raise the Creature like a child, and can shape its behavior and personality in a wide number of ways.
 * Famously, during a demo of the game at a major conference, as Molyneux was speaking, the Creature proceeded to surprise him by learning "rock + fire = extra damage" without prompting.
 * The A.I. of The Sims 3 has been noticeably improved on compared to the previous 2 games, with Sims being able to live out their lives autonomously with almost complete success, instead of doing dumb stuff like missing work because of improper sleep schedules, traveling across the house to use a bathroom instead of using the one two feet in front of them, or staring at a fire and letting it burn down the house instead of actually doing something about it.
 * Although they still miss work playing computer games.
 * In the first two games, you could delete the pool ladders (or create a one-way moat around your house) and watch as the sims all stay in the pool until they drown. Imagine everyone's shock when they tried that in The Sims 3 and the sims climbed out of the pool like you would expect someone to do in Real Life.

Sports Game

 * A glitch in the NES Lunar Ball game was recently found and utilized in a Tool Assisted Superplay. The entire TAS in question was done not by a human but by a bot that was specifically designed to find the most frame-efficient way to finish each board using what was known about the game, taking into account that deliberately performing a shot that pockets no balls reduces the number of frames spent waiting for the bonus to be added to the score. The bot stumbled across the glitch by mere luck and decided "hey, this works better". This is the TAS in question.
 * Almost paradoxically, happens in Pro Evolution Soccer a lot on the easier difficulty settings: not only will the AI let the player take his time while practicing basic skills and passing, it will also purposely decide to defend or attack according to how well the player is learning. It's most notable on a beginner's first run, as any player who has mastered these skills will obviously notice all loopholes.

Stealth Based Game

 * Thief is notable for implementing a complex sensory system for its A.I. characters, allowing guards to be aware of and respond to environmental factors such as noise, lighting, movement, and shadows. While Yahtzee was playing it, he accidentally jumped out and then leapt back in while a guard was watching him. Instead of the guard just moving on, he yelled "Don't think you can just jump back into the shadows, boy!" which, Yahtzee said, "Surprised both myself and my dry cleaner."
 * Every Metal Gear Solid game after (and including) 2 has had some MASSIVELY improved AI. When walking on metal floors, an enemy will hear it if a) they are close enough or b) if it is loud enough. If a soldier is downed and another person sees the bloodspot or finds the corpse, they will automatically kick it up to maximum security and a new guard will be sent to the area. If a guard is knocked out, they will kick it up to maximum security. If all guards have been killed, the commander will notice after a while and send a heavy-duty team to investigate. During Alert Mode, if there are blood trails on the floor leading into lockers and/or closets, the enemies will either throw a grenade into that area, or have each soldier comb each nook and crannie of the area and search the lockers (not to mention that they can HEAR YOUR HEARTBEATS and your breathing if you stand too close to the locker door!). If you are hiding behind cover, some guards will provide suppressing fire while some others will flank around you. Enemies also can have the uncanny ability to spot discolorations in the atmosphere or a floating gun if you are using stealth camo.
 * Metal Gear Solid 3 takes this a step further by adding a camo system. If a guard sees rustling grass or some oddly colored spots in the environment, they will go to investigate.
 * Also, if your stamina is low enough, your stomach will start growling If an enemy is near by, THEY WILL HEAR IT AND INVESTIGATE!!! Effectively f@#king over the player if they are out of food because your accuracy and wound healing both depend on your stamina.
 * To avoid this, Eat Snakes.

Turn-Based Strategy

 * The enemy AI in Final Fantasy Tactics can be quite good at times. Its main flaws are that it usually doesn't have good skills or equipment to work with, and it can't plan its actions multiple turns in advance, so its brilliance is limited to what the best action within the current AT list is (including spells/abilities currently charging). Fixing these is the purpose of one of the more notable Game Mods.
 * To give examples, the AI properly understands elemental absorption for healing its allies, attacking MP (or restoring it) to affect charging spells, and even bouncing spells off of Reflect to increase range. That last one is a very rare situation even for human teams. It also performs extremely esoteric actions such as placing a doomed unit (e.g. a fatal spell is charging on it that it can't escape) in front of a dead ally Mime solely because if the player uses a Phoenix Down to revive their Mime, their Mime will mimic the Phoenix Down and resurrect the enemy unit.
 * An unprepared player may be caught off guard as the AI even knows how to exploit the game's projectile rules. For example, range weapon-equipped characters can shoot enemies that are too close to be targeted by shooting at enemies standing behind their intended targets; this can even be done with longbows, but requires a major elevation difference between the attacker and intended target! The computer will occasionally mess up these attempts though- not surprising considering how hard they can be to predict.
 * Its spiritual predecessor, Tactics Ogre, also has the same. You'll hate that they averted the No Arc in Archery trope when you're fighting an uphill battle, and love it when you realize you can do the same. The PSP remake also takes this up to eleven, where the enemies know to focus fire on low-health targets, targets that will take a lot of damage such as low-levels and squishies, and to Shoot the Medic First. You can still exploit this by sending someone with no equipment out to act as a decoy. They also will send knights with rampant aura (Which prevents you from moving further than them) to body-block you and just stand there with Phalanx on (reduces damage by 90%).
 * The AI in Fire Emblem: Thracia 776 is dangerously smart. For instance, if you steal a mook's only weapon, he will run to the nearest weapon shop (if there's any that sells weapons he can use), and will actually buy the best weapon he can use and attack you with it next turn.
 * Enemy flying units will prefer to attack your ground troops from whatever range that denies you from counterattacking(if possible) and then use their remaining move spaces to fly away into terrain where you cannot retaliate, effectively denying you the chance to finish them off.
 * Similarly in Fire Emblem Elibe and Fire Emblem: The Sacred Stones, mages with versatile attack ranges will often run right up to your archers and attack at a range where they cannot counterattack.
 * In 1981, and then again in 1982, Douglas Lenat tested his learning program, Eurisko, in a Traveller: Trillion Credit Squadron tournament. Eurisko simulated thousands of battles, found unconventional ship configurations and methods, and defeated all comers. Twice. In a row. Even with notable rule changes.
 * Eurisko could have done it a third time, but Lenat decided to retire it from the tournament, since if the program had won a 3rd time, it would be the last such tournament.

Wide Open Sandbox

 * Bully Has some. Prefects don't only chase you if you break a rule, they chase other kids who break rules.
 * Dead Rising was famous for having incredibly stupid survivor AI. In Dead Rising 2, they're much, much better. They follow you intelligently and are very good with weapons. If a zombie jumps onto you, they even attack the zombie in order to save you!
 * The Rapid Response military ships in X3 Albion Prelude are some of the smartest enemies in the game. When they detect one of their race's stations are under attack, they'll jump their ships in and curb-stomp the enemy with heavy missile spam fired from 80 kilometers away. When one of their capital ships starts to take heavy damage, it'll use its jump drive to jump to safety and go repair.

UNSORTED

 * The "It's Thinking" advertising for the Dreamcast was all about this (in theory). For a football game the ad would say e.g. "It knows you like to go for it when it's 4th and goal. It's thinking".
 * A non-video game example: In the climax of The Two Towers, the enemy Orcs were programed to make the best tactical decisions possible against the tree-folk. Apparently, they figured out that running away was the best thing to do, and so the programmers had to keep dumbing them down until they stood their ground and got slaughtered like good little bad guys.
 * Some web apps are getting very clever at interpretation. This troper once made a Facebook update consisting solely of the phrase "Gorram Reavers", and FB grouped it in with a bunch of friends' comments talking about Firefly.
 * Google for something like "that film that runs backwards" or "that film with no babies".