Game Breaker/Video Games/Turn-Based Strategy

Game Breakers in Turn-Based Strategy games.

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 * The Disgaea games, (and in fact most Turn-Based Strategy games by Nippon Ichi) actively encourage you to try to break the games by creating ridiculous multi-character chain Combos and creating your own Infinity Plus One Swords, as well as gaining Over Nine Thousand levels.
 * In the third game, Adell is an extremely broken DLC character. Evility that does 30% more damage in one on one combat plus a S ranked innate attack plus loads of enemies (including story mode boss fights) that are weak against fire equals pain.
 * The DS remake of the first game makes Pleinair a playable character. She has great starting stats, good stat growth, 2 counters, good movement, and above average affinity for every attribute except defense, which isn't important because she has a %150 speed affinity which makes her almost impossible to hit anyway. She also has a %120 accuracy boost, so if you hand her some accuracy boosting armors and a gun and she can kill just about anything. Honestly, the girl can make it all the way to chapter 9 all by herself. It's slightly balanced in that she's only available during a New Game+, but it's possible to trigger a Nonstandard Game Over at the end of the first episode by losing to Mid-Boss, effectively gaining a powerful character while only losing about four battles worth of progress. And the New Game+ lets you keep Laharl, Etna, and any created characters at the their original levels, so even that isn't a problem.
 * There is also the issue of the Majin class. The Majin is hideously overpowered, having 110% proficiency in all classes for the first three ranks (meaning that all stat bonuses are 10% more efficient when equipped on them), which is an accolade normally reserved for specialist classes in their specialist stat, and 120% efficiency for the later three ranks (which is just flat-out crazy). This effectively means that they out-perform EVERYONE, at EVERYTHING. They're better swordsmen than Cosmic Heroes, better with their fists than a top-rank Eternal Fist, and better spellcasters than a Galaxy Mage(and have MUCH better health and defenses too). In fact, the only thing they aren't completely superior at is guns. At guns, they TIE with Space Marines, which are the highest rank of a class designed to use guns almost exclusively. The final rank, the Divine Majin, is simply flat-out broken and obseletes all other classes once unlocked. However, this is somewhat counterbalanced by the esoteric requirements needed to unlock the class. You need to have five different characters, of five different classes, some of which need to be unlocked themselves first, each at level 200.Since the final boss is only level 90 by default, it's highly unlikely that you'd ever manage to unlock it by accident, or on your first run through the game.
 * One must consider the fact that the Majins are really only available after you've beaten the main storyline anyway, and the Bonus Boss characters in the after-game sections are so disturbingly powerful that the Majins are practically balanced in comparison. If you get a Majin during the main game, you've broken it already anyway, as you already have 5 characters that outlevel the final boss.
 * Flonne, she starts weak, but if you give her pupils to learn all magics, give her a bow and she can nuke anyone from across the map.
 * And considering that a Galaxy Mage/Skull knows pretty much every spell bar defensive buffs, you can have all her other pupils beef up her other stats.
 * The Yoshitsuna sword makes all the other weapon types useless in the first game. It has more range than a gun, higher Attack power and capability than any other item PLUS stats boosts in all areas and, coupled with the sheer variety of skills that swords provide, it can cover almost all the area effects you need. It was considerably nerfed down in the sequel.
 * Capturing monsters. By throwing a monster-type enemy (not a human-type, unfortunately), it will join your party under certain circumstances. Seeing as throwing an enemy on one another fuses them together, adding their levels together, it takes only 8 hours to go from a level 500 character to five level 9999 characters.
 * No longer possible in the games following Disgaea 2: Cursed Memories (The remake of 2 included), as you can't capture monsters of a higher level then the main character.
 * It's possible to apply both the poison and sleep status ailments to any non-boss enemy to kill them off with ease, regardless of the level difference between you and them. As a result of this, one can clear some optional maps with extremely good rewards (Dark Sun level 1-4 of Axel Mode in Dark Hero Days in particular) far earlier then intended, and break the game with the absurdly powerful equipment and tremendous EXP rewards from them.
 * Some consider Desco of Disgaea 4: A Promise Unforgotten to be a game breaker due to her powerful evilities (Increases attack of adjacent allies by 20%, gains 20% attack per third of total HP missing, and deals 50% more damage at the expense of receiving 30% of normal mana), high stats, and multitude of long ranged area attacks that become even better after a monster fuses with her (Yog Sothoth hits a 3X5 area up to six spaces away, making it the biggest ranged area attack in the entire series). On top of that, she can be boosted even further by a Beast Trainer.
 * In Shining Force, arguably, Domingo. Let's see... he flies, he levels up quickly, he gets some very powerful magic, he gets more MP than most spellcasters, and, most unusually for a spellcaster, he gets very high HP and physical defense, to the point that even enemies in the last few battles will probably only do 1 damage if they use a non-magical attack. On top of all that, as a spellcaster, he's a prime target for the AI, so you can use him to keep enemies' attention while your other characters wail away. His only major downside is that he doesn't get to equip any weapons, but since he's not likely to physically attack anyway, that hardly matters.
 * In the GBA remake, Domingo is even more broken; because of the change to Desoul, the token instant-kill spell being a flat low chance for every non-boss enemy to a spell that has a 100% success chance for all but bosses and certain monsters, Desoul is now a very powerful and efficient spell for killing monsters - even factoring its steep 8MP cost. And with Domingo's massive MP growth, he can happily spam Desoul without ever worrying about depleting his MP pool.
 * In Shining Force 2, one of your characters, named Karna, learns a buff spell called 'Boost 2'. The spell itself is not the broken part of it, all it does is increase the affected member's defense and agility, which is nice, but not game breaking. What is game breaking, however, is the large area it can cover, allowing Karna to affect the entire party, which no other buff spell does. Because it affects the entire party, Karna earns the maximum possible experience every time it's used, no matter what level you are. This allows you to power level Karna to ridiculous degrees relatively fast.
 * Now promote Karna to the 'Master Monk' class using one of two "Vigor Orbs" found in the game and buy her a pair of knuckles, she is now a very effective front-line fighter as well as a healer, in addition to leveling disgustingly fast. Now consider that you can recruit her and do all of this about halfway thru the game.
 * The original Civilization had the Pyramids wonder. With just Masonry technology needed to build them, they allow you to change your government at whim, to any type of government (even if you haven't yet researched it), without an anarchy period. That basically allows democracy (a game breaker government all in itself) about 3000 BC. And then, if you ever need to kick someone's butt but the Congress overrules it, just start a revolution, declare war, and continue enjoying benefits of democracy the very next turn! The only thing you need to watch out for is to never study Communism, which disables the Pyramids effect, and luckily, it sits pretty high up in the science tree and you don't really need it.
 * The Civilization II Pyramids were also a game breaker as they counted as a free Granary in EVERY city you have from when you build it (right at the start of the game) right up to the end. What's that mean in real terms? Double population growth in all cities and it never expires!
 * Civilization IV still has the Pyramid wonder, with pretty much the same effect - it enables all government civics (Civ IV's equivalent of government types). Combined with stone in one's starting area to halve their cost, this changes them from "hellishly expensive" to "doable", and constructing them gives access to the representation civic, which both allows you to increase the population of your largest cities by around 30-50% for the time period you are in and doubles the research produced by scientists.
 * Some of the Unique Units in Civilization IV also have a vague Game Breaker-esque status. The Incan Quechua is available from the beginning, cheap and cost-effective against archers, making early rushes for the Incas much easier than any other civilization can pull them off. Also, the Roman Praetorian, which is an early Classical Age unit... with an unit strength more common for the Medieval Era.
 * Civilization II gives a number of game breaking wonders, such as Leonardo's Workshop, which upgrades all your units to more modern equivilents when the necessary technology is researched.
 * Civilization III had the Small Wonder "Wall Street". Its effect? Giving you 5% interest on your treasury per turn. After a few turns you had no money issues for the rest of the game, as long as you kept your treasury above zero. It was later fixed with an Obvious Rule Patch, capping the generated income from the building to 50 gold.
 * In Civilization I, there was supposed to be a major disadvantage to Republic and Democracy: you have to accept any peace offers. But there was a very simple counter: just don't ever meet with representatives from other civilizations. In Civilization II, they tried to eliminate this tactic by allowing a civilization to force a meeting with you any time you move a unit next to one of theirs. Since this ability was exercised most commonly after you take an enemy city, the response to this was to eliminate the defenders from several cities, then take over all of them at once.
 * If another civilization is getting ahead of you technologically, you can take over a city (which allows you to steal a tech), move all of your units out of the city, let them take it back, then retake it before they have time to fortify their troops. Rinse, repeat. Add in some tech-stealing diplomats, and you can eliminate several centuries' worth of technological lead in a few turns.
 * Civilization I had a bug that allowed each Settler to perform any one Settler action each turn (some of them were intended to take more than a dozen turns). You could also, strangely enough, build railroads in the middle of the ocean.
 * In Civilization II, you can produce unlimited Hides caravans and re-home to a city with high trade. With an advanced civilization, this can result in a new tech each turn, and more money than you'll know what to do with. The game designers apparently tried to prevent this by disallowing re-homing of caravans, but forgot to eliminate it from both menus.
 * In Civilization II, having both Railroad and Explosives completely changed warfare. If you had enough Engineers, you could build a railroad across any distance of grassland or plains in a single turn, then use that railroad to transport units across the railroad (all in the same turn). Your artillery only has one movement point? That won't stop you from using it to attack a city a dozen squares away. You can also use a chain of Transports to move a unit across any distance of water in a single turn.
 * Also in Civilization II: The UN was a crucial Wonder. Not because it was particularly useful (you could force other civilizations to make peace with you, but that was rather pointless since they'd then just break the treaty a few turns later), but because if another civilization gets it, having them constantly force you to make peace is a hassle.
 * In Civilization Revolution, the simplified mechanics provides a number of opportunities to completely dominate the AI even on the most difficult setting. And the Leonardo's Workshop wonder is so overpowered, since it upgrades all your existing units. Given the right circumstances, you can destroy any AI. First, always produce as many cheap, weak units as possible. As you're doing this, follow the path on your technology tree to discover the internal combustion engine. Time the building of Leonardo's Workshop so that it occurs right after you discover the engine and gain the ability to build a tank. All those cheap warriors you've been building since the beginning? They're now tanks. The game is over in 2 or 3 rounds max.
 * Civilization V gives us Bushido, the Japanese special ability, which causes units to maintain full defense and attack stats even while wounded. If this wasn't overpowered enough, it's possible to combine this with the Populism social policy, which grants a 25% damage bonus to wounded units. In other words, damaging Japanese units in these conditions actually makes them stronger.
 * In Civilization III the Persians are considered by many to be the most powerful civilization in the game because they possess the Industrious and Scientific traits, which grants them bonuses to both production and research. Additionally, their unique unit, the Immortals, are the single most powerful ancient age offensive unit (it isn't until knights come along that a unit possesses more offensive power). The sheer power of the Immortals makes it easy for the Persians to conquer other civilizations during the ancient age and even well into the middle ages.
 * In Sid Meier's Alpha Centauri the supply crawler unit, which the computer never uses, gives the player a major advantage by itself. What makes it a game breaker is when you upgrade cheap crawlers and contribute them to builder wonders, because the cost of upgrading units is about 8 times cheaper than trying to pay for buildings. This makes it possible to build wonders, even the late game ones, in a single turn. Even at the highest difficulty, you civ score should skyrocket right after getting the tech for crawlers.
 * Similarly, you can just abuse the fact that the AI never uses Supply Crawlers, by using them as they were intended, ad nauseum. Supply Crawlers act as if you were harvesting resources from the square it's sitting on(though only one resource at a time, as opposed to the usual three). However, by planting forests, which have a chance based on your Planet rating and eco-damage to automatically spread, you can plop crawlers down in squares your cities can't reach and use them to gather minerals to make supply crawlers to gather minerals...
 * And this says nothing of the use of "Thermal Borehole" improvement... as a weapon. Industrial development is normally limited by Gaia's Vengeance, including rapid sea level rise. Boreholes tear the environment a new one. By using probe teams - saboteurs - in every enemy city to destroy the one building that lets them survive submersion, it's possible to eliminate EVERY OTHER CIVILIZATION IN THE GAME AT THE EXACT SAME TIME without declaring war even once, by using thermal boreholes to raise global sea levels until everyone drowns.
 * The late game in Master of Orion 2 had a pretty obscene example of this with the Phase Cloak/Time-Warp Facilitator Combo. Alone, the Phase Cloak rendered your ships invincible and invisible until you opened fire, at which point you would have to spend an entire turn doing nothing to get the cloak back up again, while the Time-Warp Facilitator effectively gave you two turns to every one of your opponents. (ie: Your Turn 1 -> Your Turn 2 -> Opponent's Turn 1) You can see the unfortunate side-effect of this a mile off, right? By using your first turn to open fire, then your second turn to recloak, you could annihilate an enemy fleet with utter impunity, without them being able to lay a single finger on you. Thankfully, this was changed in a patch.
 * Also, the counter was quite obvious: Use a Phase Cloak on your own, but don't use a TWF. This way the enemy ships have to keep the cloak up for twice the amount of turns, which means their cloak will run out of energy first.
 * In addition there was a starship component called a Structural Analyzer, which doubled all damage that struck the target's bare hull. Not a Game Breaker on it's own, but there was also a component called the Achilles Targeting Unit, which caused all attacks to ignore the target's armor. Combine these with weapons capable of bypassing shields and season with some more general damage/accuracy boosting components and you had a warship who could wipe-out 10-20 ships by itself in a single round (a more 'conventionally' equipped ship takes 2-3 rounds just to destroy a single ship of similar size).
 * The Guardian of Orion can be defeated very early on with large numbers of MIRVed Merculite missiles. The battleship you get as a reward for this will, at this early stage, be so powerful that the other races can't touch it, allowing you to wipe the floor with them. Gyro destabilizers can also be used for a game-breakingly early Guardian kill because they do completely plain structural damage and ignore defenses.
 * Ditto Stasis Field Generator. It can be used rapidly incapacitate most of the enemy fleet and then tear them to pieces one by one.
 * The Custom Race option can be used to achieve a Game Breaker effect: simply slap both the "subterranean" and "aquatic" bonuses on your custom race. (Never mind that it makes no biological sense whatsoever.) The result: a race that can out-breed any other, given a planet with water. And since most of the easily colonizable planets are "terran" or "aquatic" by default... And more people means more production and science. Plus the subterranean bonus gives a big boost to ground combat when defending against invaders.
 * For blitz, "UniTol" (Unification + Tolerant). It costs a lot of points, but you have worker production bonus (all-important before you get enhancements and still quite nice later), don't care about morale and environment (either may be less of a problem in late game, but early on holds you back), can use Toxic planets, and will not care much about spies when you'll meet others. Start expanding early.
 * The Creative racial trait borders on game-breaker, requiring only 6 of your 10 available points to buy but allowing you to research all of the technologies available, not just one out of every two to four options given. Like, say, the various technologies referenced in this section.
 * In version 1.2, the Plasma Cannon (specifically, the Heavy Plasma Cannon) was this. Whoever decided to make it that small apparently failed to realize that Enveloping doesn't just mean four times the shield penalty - it means four times the damage. And the Heavy mod largely negates the weapon's worse-than-usual range dissipation. It was entirely possible to lose a late-game battle solely by researching Disruptors and having all your bases "upgrade" automatically. (In version 1.31, they made the thing 2.5 times as big, and it was still approximately tied with a fully tricked-out Phasor as the best beam weapon in the game.)
 * When combined with the Structural Analyzer and Achilles Targeting System described above, and optionally a Phasing Cloak, facing everything the enemy can throw at you with a single doom star thus equipped is basically dynamiting fish in a barrel.
 * Artillery has natural no range dissipation, and Armor Piercing mod: not only armor on the target doesn't matter at all, but its drive usually breaks before hull hit points are gone. Theoretically is negated by Heavy Armor early on. Practically, AI ships almost never has it. So good drives to keep the distance, Mass Driver, 1 more level in Force Fields or 2 for auto-firing, and never mind missing jammers or shields: small mass drivers are good point defence and heavy ones do flat 9 damage, so you can plunder missing tech from crippled and boarded ships with shields up to class V (3-4 levels over such guns).
 * In Galactic Civilizations II, the Psionic Beam, which does 4 times as much damage as any similar-tech weapon. This is justified by you having to be Evil to get it, though its use is still frowned upon.
 * Also, in Dread Lords and Dark Avatar, the Mind Control Center wonder is bugged and instead of giving its advertised effect (near-instant defection of influence-pressured planets), it gives an even better flat 100% boost to your civilization-wide Economy. Of course, you again have to be Evil to get it - basically making Evil the game-breaker alignment. Of course, in the Twilight expansion, both are fixed.
 * Psicorps in X-COM: UFO Defense. Hard as hell to acquire, as you need to capture a psi-using alien that is blasting you with said psi-abilities (often straight at the easily affected guy that it can't even see), interrogate the alien, research the tech, build the required buildings, then wait until the month ends for results from said building. If you're extremely lucky, you'll have this by the 4th month, else you might have to wait until the lategame aliens show up. But it was well worth it. First off, you get to see the Psi-Defense stat of your units, eventually allowing you to get a team entirely immune to psi-attacks. The abilities themselves are powerful as well. The more accurate skill causes the target to panic, making them an easy kill. The other skill is Mind Control, a skill so powerful that you can use it to win the final mission on the first turn singlehandedly. Apocalypse nerfed it from Game Breaker to merely stupidly powerful (the second was merely so hard you actually needed it to win on the higher levels). You can use it to mind-control a zombie, kill it, then you have a pet Chrysalid.
 * That's why UFOextender (and OpenXCom) have "Psionic line of sight" option. Also, "Psionic training at any time" (it still takes 30-60 days, but start when you're ready).
 * And then there's the Blaster Launcher, a weapon that could send a missile out the door of your transport, over the heads of your units, down through the door of the UFO and up the elevator shaft to blow a hole in the otherwise impregnable UFO hull material. Or alternately just take out a Sectopod in one shot. It's successor, the DPT Launcher, was nerfed in a way you can only fire it underwater... unless you consider that you troops can still reaction-fire it! Not to mention that one of the resources necessary to make ammo for it is more abundant in the sequel.
 * Avenger/Leviathan craft. Though the basic interception unit is so weak that every alien craft can outrun it, these two can outrun and outgun even the strongest alien craft - with a bit of a twist: if they survive, they become TOTALLY USELESS for about a month until repairs are done (plus they consume valuable resources to even keep flying). Meanwhile, aliens are happily wreaking havoc...
 * You can actually stick any craft weapon on any ship capable of dogfighting. Cue the Plasma Cannon: not overly powerful or fast, but it's range exceeds that of any UFO except the largest Battleships, it's ammo is free, and it has plenty of the stuff. And you can order your craft to fire from their maximum combat range, hence making even your lowly Interceptors effectively invulnerable. Battleships are immune to this tactic and do deal massive amounts of damage, but this can be mitigated by attacking them with multiple ships at the same time - the damage gets spread out (dividing repair times amonst the ships present) and the UFO goes down faster (meaning it deals less damage in the first place).
 * Smoke grenades are remarkably effective at decreasing the aliens' initial advantage; just drop it at the foot of the transport's ramp, before leaving, and the chances of the aliens' reaction fire hitting the redshirts drops drastically. Proximity grenades are sworn by for many players to mine UFO exits and buildings aliens might be hiding in. Both together are a potent combination, especially if you've mined a Zombie that turns into a Chrysalid.
 * Not to mention X-Com Apocalypse's Toxigun. An insanely powerful weapon that costs just a pair of APs per shot to fire and completely surpasses the aliens' Disruptor Shields. After researching this and the Personal Teleporter, the game pretty much turns into administering point-blank euthanasia shots to the aliens. Even more ridiculously overpowered Alien Gas Grenades and Alien Gas Rockets are available late in the game, provided you manage to . The Personal Teleporter allows you to instantly teleport your soldiers anywhere on the map, and it is not uncommon to win the mission on the first turn considering that your soldiers are likely people of mass destruction by the time you research this item.
 * Spiritual Successors UFO: Aftermath and Aftershock had warp weapons. Subverting the previously established player knowledge of armor=longevity, warp weapons inflict greater damage if the target is wearing armor. Devastating when first encountered, when the weapons are reverse-engineered by the player, they become the single most devastating weapon in the game, capable of one-shot killing anything, as enemies are always wearing heavy armor at that point. Greatly toned down in UFO: Afterlight, as the player only gets two warp weapons, with six shots each that can't be recharged during a mission and low base accuracy.
 * UFO: Aftershock has psionics with level 3 sniper, using the .50 calibre rifle with accuracy add-on and accuracy boosting psi-gear has a 1.1 - 110% chance of a torso hit. A headshot is merely 100% chance of instantly killing the standard mutant or Wargot. Also you can field a whole team of these girls, and depending on the status of your install the accuracy aura buffs may stack. Gets more insane if you give them Katanas against Wargots in room-to-room combat...
 * Even against enemies that could take multiple headshots and survive, a called shot to the head is considered a critical hit and topples the target over (there are enemies with "knock back resistance" ability but they are not common). Guess how much time it takes to stand up? Approximately same amount as making another called shot. If there is another enemy between sniper and target, then there is chance of hitting the enemy blocking vision, and if this happens, that enemy will be critically hit as if it was intended target of called shot, even if it is impossible to make called shot on that enemy. Very effective against mutants and Starghost combat drones.
 * UFO Aftershock has also short range game breaker. Guns Akimbo. Well developed Cyborg/Ranger/Commando with 2 MP5 SMGs, armour piercing ammo and proper implants has greater range than assault rifles, 10 shot long burst (each shot has individual check for critical hit meaning that at least one critical hit in burst is virtually certain), very low aiming time (if enemy comes from beyond the corner it is possible to kill him before he finishes turning around) and (due to bug) insane movement speed, team him with Human Scout/Ranger/Commando who has much lower range but (even) higher critical hit chance and can spot living target from half the map. That duo can: shred anything into pieces at short range, suppress and outgun anything at medium range, rush from cover to cover so quickly that no enemy can even aim at them and obviously spot targets for snipers. Only drawback: huge ammo consumption.
 * The Life faction's archers in Lords of Magic have a longer firing range than any other unit in the game, including wizards. So when Sauron Balkoth decides to raid your kingdom, all you have to do if you're playing the Life faction is to station tons of archers and arrow-spam him before he can get any spells off, then retreat when he's dead. As the goal of the game is to kill him, you win.
 * In a custom start, a water mage lord can start with the Staff of Drowning legendary artifact that can decimate enemy armies.
 * Lords of the Realm 2 allows you to raze a foe's crop fields to annihilate their agricultural economy. There's also a minor exploit that allows you to produce armies consisting of only one soldier (normally a minimum of 50). Taken separately, one is a relatively balanced tactic and one is pointless. Combined, you can quickly swarm over your enemy's fields and cause a serious amount of damage with only a few soldiers.
 * In Jagged Alliance 2 fighting at night pretty easy if you have a squad (with the Night Ops skill) and equipment (NVGs and break lights) for it, as enemies have a low field of view, accuracy, and have a tendency to run straight at your mercs if you attack them from a good enough distance (most likely because they are trying to get in range to counter attack)
 * The character creation "personality test" (which determines your starting merc's special abilities and, well, personality) lampshades this: One of the items you can pick from an army surplus store is "a pair of night vision goggles and the illustrated manual 'Daytime - an unnecessary hazard'".
 * In unpatched Heroes of Might and Magic V, the Necromancers were obscenely powerful because of an unfortunate synergy between the fact that their Necromancy skill allowed them to raise a sizable percentage of all living enemy creatures as skeletons, in a game that allowed you to upgrade your skeletons to skeleton archers on turn 2. Some neutral-monster-bashing later, and you have a stack of archers numbering in the thousands, growing to the tens of thousands, in a game where a single stack of the weakest units numbering 1000 is (supposed to be) a rare event. Cue one-shotting anything. Cue inevitable nerf, by restricting number of creatures raised per week and causing enemy casualties to be raised by creature level. Yes, necromancers were nerfed by allowing them to raise more powerful creatures.
 * Which is NOTHING compared to those fucking ghosts from Heroes of Might and Magic II. For every unit they kill, a ghost is created. Combined with the large number of wild low level creatures with low defense, building up a 1000+ army of ghosts is very easy. This makes maps where your enemies get ghosts all the more painful since if you lose a single fight against them, their armies can potentially get STRONGER even if you kill all of their other units. I'm looking at you Ghost Planet...
 * Demonology and the "Summon Elemental" spells in Heroes of Might and Magic IV border on this. Especially if the character with the spell or ability also gets their hands on a Demonary or Ring of the Elementals.
 * Master of Magic has so many Game Breakers, they almost balance each other out again.
 * In the release version, a single unit of Paladins could slaughter just about any enemy in the game. They combined the speed of cavalry, excellent armor, powerful holy weapons, and the very rare ability "Magic Immunity".
 * Magic Immunity, in the release version, made you immune to hostile magic, even "mundane" magical ranged attacks and magical weapons, which was nearly everything in a game about wizards. On top of all of that, as they were considered a mundane unit, you could start making them as soon as you had the right buildings set up, but only if you played as high men. The later patches weakened Magic Immunity to simply be an enhanced chance to resist magic, but they were still quite effective.
 * To clarify further, the bug was that a unit with magic immunity was immune to all attacks from magical creatures, even non-magical attacks. It was supposed to make you immune to attacks like fire breath and stoning gaze as well as magical spells, but not claws and teeth. So an immensely powerful monster like a Great Drake simply could not harm a unit with magic immunity. The last official patch fixed this bug.
 * Sorcery gives Flying Invisible Anything with spells (and equipment for heroes). Flying Invisible Warships unlike Paladins weren't nerfed in the patch. If Flight is dispelled on a wrong terrain units are killed, but Spell Lock is also a Sorcery spell, so Flight users are likely to have it too - and even if not, there are 3 stacking bonuses against dispels.
 * Life magic combo of Morale + Income bonuses. Nodes may be taken by Guardian Spirit (Life summon) from common Magic Spirit, but not vice versa, so Life wizards have an advantage of irreversibly robbing anyone else. This may or may not be balanced by the chance to overtake and getting the units there in the first place, depending on map size and magic setting.
 * Though they don't always remain useful, if the opponent has Corruption or Warp Node spell (and can get it through the node's countering aura). Even then, mass fall of nodes may mean that Life and Death wizards harvest double mana from temples, those with cities of magical races get mana from population, and the rest have to either convert gold - if they have enough - or do without.
 * Some strong enchantments, like Time Stop or Zombie Mastery. Hard to cast, but upkeep costs are modest.
 * Death has two spells giving Weapon Immunity, Wraithform and Lycanthropy... but worse are Evil Presence (crippling unrest) and Warp Node (it sucks mana back in, and the victim needs a lot of mana to have a good chance to disenchant it - a vicious circle).
 * Black Channel turns a unit into undead; it now no longer needs any upkeep except for one mana, but can't heal. Use this on trolls...who still regenerate. No more massive upkeep, but still healing benefits! (Since undead don't gain XP, you'll want to train your trolls up to elite first, but that's easy enough).
 * High Elven longbowmen do full damage at any range. Two longbowman units can often clear the field of enemies entirely without magic, and then you give them alchemical assistance.
 * Undead Hordes in Disciples 1&2. One can get ghosts with physical immunity pretty early in the game. And then easily kill all those giants, trolls and krakens for large amounts of gold and exp, which in turn would allow to kill more dangerous enemies, such as dragons and enemy heroes. All handicaps enforced by such strategy are counterable. The most practical way to deal with such party is to bombard them with most powerful spells available, which works only slightly better due to the fact that your whole army consists of Squishy Wizards (while the survivors of normal army would be easy pickings for exp). And computer doesn't do that.
 * In the Mega Drive/Genesis port of Heroes of Might and Magic: King's Bounty, you're racing against the clock to defeat all the bad guys and save the king. Luckily, there is a spell called "Time Stop" that briefly freezes time. The Sorceress has many spell slots. The result of using these two together is that you can leisurely sail around picking up money (which always respawns). It also freezes all the random encounters on the map, letting you either easily avoid or only attack the weak ones for easy gold (and possible recruits). Yelling "Za Warudo" while using this exploit is stupid.
 * In Valkyria Chronicles the "Scout Rush" tactic (ignoring most of the enemies in favor of dashing across the map with scouts (who have by far the most movement points) and capturing the enemy base) is a mild Game Breaker from the beginning of the game. As you progress through the game you will unlock the Elite level for your scouts (even greater movement points), the "Caution" order (greatly decreased damage from enemy interception fire), the "Demolition Bost" order (lets scouts skill tanks with their rifles), and potentials including "Resist Crossfire", "Double Movement", and Alicia's "Mysterious Body" (free healing). By the time Windmill Plaza is unlocked as a skirmish, you should be able to complete it with Alicia solo in a single turn. Much earlier, the Kloden and Fouzen skirmishes can both be beaten by a team of three scouts in two turns.
 * Then there's Alicia herself: her accuracy and evasion stats are absurd, and the combination of Mysterious Body and mean it can be very, very hard to kill her. If you're not worried about how long it takes and leaving the rest of your command-point-bearing officers in the base, Alicia is quite capable of completing several missions by herself.
 * In H-Game Sengoku Rance, you'll see a few people who will mention Omachi, Kenshin + Natori + Uruza + Aburako Dosan, and Yuzuhara Yuzumi + Mouri Teru pop up in discussions on who's the game breaking unit.
 * To explain this better; Omachi is absurdly broken. She's easily the strongest diviner in the game (fitting since she's the former queen of the Youkai empire) and her second Lightning ability is the equivalent of an I Win button. For just one turn of preparation (which can only be canceled by two ninja attacks), she can deal 150% of her usual damage to all enemies.
 * The Kenshin + Natori + Uruza + any monk with convert action is also absurdly unbalanced. Kenshin has a passive skill that lowers all enemies moves by one and boosts her stats. Natori has a spell that, given one turn of preparation, kills 30% of each enemies troops but has the downside of taking up all of her moves. Uruza also has a hit all ability that lowers all moves by one again. The Monk can then use convert action to let Natori and Uruza have multiple uses of their skills.
 * The Yuzuhara + Teru combination isn't as broken as the other two examples but it's still absurdly powerful. Yuzuhara has a very powerful short range attack that has a chance of annihilating the enemy unit. Teru is one of the best foot soldiers in the game thanks to the Ally Guard Plus ability (Very high odds of her unit taking an attack aimed at another unit) and Counterattack Rate Up 2 which give a massive increase to her counterattack damage. When equipped with the Dragonfly Cutter, she deals insane amounts of damage when counterattacking.
 * Tactics Ogre has too many to count. Archers are available early on and will be useful for the rest of the game; unlike any melee unit they can attack at ridiculous range (greatly enhanced by having high ground) and aren't subject to counterattacks, can walk through water, and do just as much damage as a melee class. Mid-game you have summon magics which can basically one shot a target. By the end of the game you just pick how you want to be broken - do you prefer to kill everything on the screen within a few turns with dragon magic, or do you prefer to exploit the Retissue spell to make a character with 10x the stats of anyone else who can wipe out the entire enemy party before they even get a chance to do a SINGLE MOVE?
 * The PSP Remake removes the Retissue tactic, but some characters still manage to be overpowered, such as Canopus, who is a winged human who has high movement, is unrestricted by height and can be turned into one of the strongest archers in the game provided you have a class mark for it...which is 300 Goth...when an average battle rewards you with several thousand. Canopus can also be kept as a Vartan, allowing him to use a bow and axe, but they both need to be one handed and they don't do as much damage...but give him an absolutely amazing movement range. Did I mention you receive Canopus on the 4th mission of the game? The first 3 missions are all automatically performed, you can't lose.
 * Knight Of Lodis had that any class could equip any weapon. Simple, right? Yeah, but then you've got a ghost that teleports to the target, floats, and uses a hammer. Or you can just use two insanely powerful spears (The second-most powerful weapon (after the four Snapdragons) in the game, the Spear of Longinus, is a spear.) and have your spear-using characters fight each other, hitting the target in the middle twice. (Does not work on Shaher, who stays in the corner.) And then there's Summon Magic...
 * A few more for KoL: The four Snapdragons are on a completely different plane of existence compared to all your other weapons. You'd be very happy with a weapon of attack 60. Snapdragons: attack 75 right off that bat, and then you can improve that AND give your character stat boosts and special abilities by 'snapping' specific classes and characters. The Ninja and Swordmaster classes are both stupidly overpowered: Ninjas move three times faster than any other character, are available at the beginning of the game and have an insane evasion score. Swordmasters are the same as Ninjas, but trade a tiny bit of speed for the ability to equip any sword in the game, and are cast buffs or status spells. Including Time Stop (Stops time for the enemy team) or Teleport (teleport), which are already Game Breakers of themselves. Then you have sword techniques that cost a tiny bit of HP to use, but easily allow you to hit the damage cap if you have a Snapdragon... by the end you can beat the last boss with your main character and another (to use the Lance of Longinus to break the last boss's invulnerability field). In three turns (one turn to get there and break the field, two turns using of the time-stop special technique combo).
 * Odium has the Attracting Device. When you deploy it on the ground during battle, monsters become hypnotized and won't attack you, instead trying to reach the device as fast as possible, thus earning you several turns of blasting them to bits without fear of retaliation. Some monsters are immune, but most aren't (including, ridiculously enough,, making several potentially tough fights a doozy.) A fun thing to try is surrounding the device with your men to keep enemies from ever reaching it...
 * Milanor from Yggdra Union gets very strong by the half of the game. Enough that his attack can top any kind of enemy even though he has a disadvantage in a weapon triangle rule. And he's one of the main characters you need to use in every battle.
 * Cyber Storm has two main game breakers:
 * Most of your HERCs can mount up to four accessories. One accessory reduces an enemy's accuracy against that HERC by a flat 25%. Putting four of them on every HERC would turn the entire opposing force into Imperial Stormtroopers. The sequel changed these accessories so that smaller and lighter HERCs gained much more benefit than heavier ones.
 * In multiplayer mode, forces can be restricted by the number of credits spent in building them. This is fine for HERCs, which have standard equipment costs and never depreciate in value. The BioDerm pilots, however, have finite lifespans, and their value is dependent on the number of years they have left to live -- not on their skills or rank. Through a bit of grinding, it's possible to enter your multiplayer battles with an elite pilot force (with 1 month before everyone's natural deaths), and more credits redirected to better HERC equipment, while still adhering to the same maximum credit restriction as someone with fresh pilots and weaker HERCs
 * In Star Trek: Birth Of The Federation, all factions have more or less equivalent ships with slight differences in speed and firepower. However, the game balance is way off. For example, nearly all Romulan and several Klingon ships have cloaking devices, which gives them a free turn at the start of battles, which often decide the outcome. Their ships are also invisible on the strategic screen. However, the Romulans are hampered by their extremely slow speed. Then you have the Defiant-class heavy escorts, which only the Federation has. No other faction has an equivalent class. The Defiant has superior firepower (higher than that of a Sovereign) and superior speed. The proper use of these can result in pretty one-sided battles.
 * The Romulan scouts could be potential game breakers as they are fast, long range, cheap and can cloak. Build enough of them—like 45 or so—and the fleet can take out a Borg Cube in their opening volley.
 * Record of Agarest War has quite a few of these:
 * The first one is Ellis who just needs to get to level 25 to get her second Limit Break Regeneration. What it does is that it fully heals all your party members in the screen. Nothing much to it right? What makes her into Game Breaker status is her attack range going up to 10 in a grid where it's at 12 at most! Link her with another character and watch as you slaughter enemies left and right at anywhere thanks to her range.
 * Next is Plum and her second skill Maiden's Prayer which you get as soon as she joins you (she's level 40). What it does is that her skill gives the other party members SP, sacrificing her own. Pump up her SP in the first turn using the other party members, bunch them together, and let loose her Limit Break. Seeing as you've pumped up the other members by them getting 5 SP per them getting Plum's SP up to 200, they'll reach the 250 SP mark in no time. In which you can destroy enemies left and right. You'll only get an A rank at most, but considering the fact that it's a miracle to have a S Rank on bosses, this is pretty much a godsend.
 * Horde all your PP, start a New Game+, and pump up Leonhardt's Strength stat all the way and the only ones you'll have a hard time are the first few battles (and half the time in generation 2 seeing as he's not in your party at this point) until you get his powerful Unleash All.
 * Speaking of which, Unleash All can also be a potent Game Breaker by itself seeing as party members who are down to 25% of their HP will have an obscene raise of all their stats.
 * Due to the game's rather primitive and sometimes crippling AI it is possible to win every single game in Hogs of War by poisoning the enemy using a gas grenade and then using the Scout/Commando/Hero technique Hide to simply wait out the clock. Using this technique you can even defeat the otherwise ridiculously strong Legend class without sustaining hardly any damage whatsoever. Coming in at a close second on the crappy game mechanics you can exploit bandwagon comes the Spy class Pickpocket ability. Steal the bazooka or sniper rifle off an enemy Hog and they become near enough completely harmless.