Last Lousy Point

This is the bane of all players seeking Hundred Percent Completion and Gotta Catch Them All.

While most, if not all, of the other points that count toward completion are relatively straightforward or easy to get, there always seems to be one or more that just, well, isn't. This could be because the Solve the Soup Cans or Stock Lateral Thinking Puzzle is just far harder than the other puzzles in the game (and possibly harder than the developers intended). Or it could be because it's extremely difficult, time-consuming, frustrating, or all three to do. Or it may be really well hidden or very easily missed and possibly Lost Forever if one fails to get to it in time. Or it could be some combination of all of those.

This is usually done to give a player a reason to come back and keep playing.

See also Missing Secret, which is when players are inadvertently given the impression there's a Last Lousy Point that doesn't actually exist, Replay Value, which is what this is (trying to) give, and Guide Dang It, which is what a player may have to resort to to get that last point. When the reward for the point is an achievement, this becomes That One Achievement.

Action Adventure

 * Peasant's Quest has one in response to . And several more just because.
 * Castlevania: Symphony of the Night could be a real pain about these, especially with the one that required to unlock. Certain parts of the map you would never need to explore were thrown in just to make 200% a daunting task. Some needed glitches to access, making the true total 210% 425.5% and rising.
 * Mudman, if you want to complete the Enemy List. It can only be summoned by the Lesser Demon boss that is fought in the first castle. And its inverted castle versions only replicate themselves.
 * All hundred Stray Beads from Okami. Not only do the first 99 take considerable multitasking (including an infamous, massive Boss Rush; Blockhead Grande, and some incredibly annoying racing minigames), the hundredth is given to the player upon completion. Meaning the player doesn't get to enjoy the reward of collecting all hundred beads until during a replay.
 * Beating Blockhead is nigh impossible without cheating: it can be sorted out by recording with a camera all eight flashing dots, pausing the game and then slowly replaying the video so you can accurately pinpoint each location with the Celestial Brush.
 * There's also feeding every animal (one of which can be Lost Forever), catching every fish, growing every clover, unearthing every treasure and acquiring every Celestial Brush Technique. Clovers and treasures aren't recorded, though.
 * After you grabbed all of the Heart Pieces in The Wind Waker, along with locating every treasure chart and the treasure it leads to, there are still things you might want to dig up. Namely, more treasure. Spread across the Great Sea are uncharted treasures identified only by a small ring of light on the surface and none worth more than 50 Rupees. If you really want that Hundred Percent Completion, you just have to scan the entire ocean; not to mention the chests hidden on land. Oh, and don't forget that some of the light rings only appear at night. Did I mention the Great Sea lives up to its name?
 * Poe Souls in Twilight Princess are much the same: getting all the Heart Pieces isn't that difficult because you can ask the fortuneteller for hints, but Poes are much more numerous (there are 60 of them) and in much more obscure places. And the ones above ground outdoors can only be caught at night, so if you're in the right location at the wrong time...
 * On the other hand, knowing what you need to do to get a Piece of Heart is one thing; actually pulling it off can be quite another.
 * Averted in Links Awakening: there are 26 Secret Seashells, some of which are only temporarily available, but there's only any point in getting 20. After that, you can't even get any; they'll just turn into Rupees.
 * Castlevania Aria of Sorrow has several, depending on which aspect of the game you're trying to get 100% in. For getting 100% of all monster souls, there's Sky Fish. This monster only appears in one obscure and optional room, and appears so briefly that you'll have to stop time to kill it. By the way, to get the ability to stop time, you have to get the one thing that makes you immune to being frozen in time and then get the soul of the one Chronomage in the game in a corner of the castle.
 * In a similar vein, the Tsuchinoko. Unlike the Sky Fish, you can kill it without stopping time, but it's really difficult because a.) it has a buttload of HP and b.) it tends to disappear the instant it sees you. Equipping the Nemesis soul helps with the latter, but it's not a sure thing.
 * For getting 100% of the map explored, there's a secret area. To get into this secret area, which is behind, you have to equip the soul that lets you   while equipping one of the few souls in the game that lets you.
 * For getting 100% of all items, there are a few items that can only be found on hard mode and a few items that you get for beating boss rush mode ridiculously fast.

Adventure Game

 * This goes all the way back to Colossal Cave, in which the Last Lousy Point is obtained by . People actually used to step through the game with a machine-level debugger to try and figure this one out.
 * Hearing gamers' screams, later editions of the game (e.g. the MS-DOS edition) added an address label telling you where to put it.
 * As a result, modern Interactive Fiction games often intentionally invoke this trope with a obscure and completely unnecessary action providing the Last Lousy Point (whereas all other points may be necessary in order to complete the game). The official or in-game solutions generally hang a lampshade on the Last Lousy Point, calling it such by name.
 * For example, in the original mainframe version of Zork, the Last Lousy Point was obtained by sending off for a brochure. When it arrived in the mailbox, the value of the stamp was "One Lousy Point".
 * Pretty much every Sierra adventure game ever.
 * For instance, looking at a six-pixel tall jogger who appears intermittently in the background (Leisure Suit Larry 2); searching every bit of evidence, sometimes twice (Police Quest), defeating every single type of random encounter at least once (Quest for Glory) and performing every required action at the earliest opportunity (Space Quest 5).
 * Even the two Eco Quest games, designed for a younger audience, have pixel-hunting puzzles that require you to keep your eyes open in EVERY scene if you want Hundred Percent Completion. The second game is much worse with this, as you sometimes only get one chance to record an item into your in-game encyclopedia, and they can be pretty obscure within a scene. And yeah, each item is worth one point.
 * The gold trophy "Perfect Crime" in Heavy Rain. Here's the requirements in a nutshell: Oh, and you can't skip any chapters while doing this.
 * Ben Jordan 2 Deluxe has a point you're virtually guaranteed to miss the first time through: . The Point of No Return doesn't help either. Might be justified, as getting all the points unlocks.

Driving Game

 * Crash Team Racing has a Last Lousy Relic. You need all the relics for a rematch against Big Bad Nitrous Oxide, but to get the last relic you needed to unlock a secret race, which required 5 gems. Each gem in turn requires 4 CTR tokens and then a win in a four race tournament. The tokens and gems do count toward completion percentage, though.
 * Oddly enough, CTR actually allowed players to score over 100% completion if they achieve high enough scores in relic races.
 * Incidentally, if you're looking for "not worth it" in CTR, look no further than the Oxide time trials. You don't even get Oxide for beating all of them, just a shortcut to the scrapbook.
 * Burnout Paradise gives you all the fun of trying to find 400 gates to smash through, 120 Billboards to hit and 50 super jumps to land. The Big Surf Island DLC isn't really fairer because if you want the best car in the game, you have to complete a staggering 500 online challenges. Bear in mind that half the server will be full of whiny 8 year olds who will NOT cooperate, and good luck getting the Jansen P12 Diamond.
 * In Need For Speed Most Wanted, in addition to completing your car garage and fully tuning them, and beating the game, you also have a list of "police chase" milestones to beat. One of them (be in a "hot" pursuit for 30 minutes and escape successfully) is almost impossible to do, simply because the longer you run from the cops, the more proactive they'll be in shutting you down.

Fighting Game

 * The Diskun Trophy in Super Smash Bros Melee is not worth the effort, nothing that doesn't pay you by the hour is worth it. Ignore that trophy, you'll thank TV Tropes.
 * That pales in comparison to viewing all the bonus messages, which requires completing 1,000,000 VS matches. Yeah, you read that right. Thankfully, this is not required to complete the game unless you're a total snob.
 * As an FYI in regards to Diskun, it requires you to get every single point bonus in the game. Click here for the list of point bonuses. It's worse than it looks, since many will never occur in a normal match and are difficult to get when you are trying. Its obscene.
 * The Subspace Bomb Factory (lower) in the adventure mode of Super Smash Bros Brawl. There are two specific treasures which are difficult to get. One requires using a character who can wall jump in an inconspicuous hallway next to a switch which clearly shows that you're supposed to turn around. The other involves going through a moving door in a dangerous scrolling section, bouncing on a trampoline off the top of the screen (which would normally kill you), using your double jump to get even higher, then attacking to break open the box. Both boxes randomly generate a trophy, which you probably already have, so they don't really do anything other than letting you have a 100% completion score.
 * Let's not forget the stickers, where if you miss one, you'll be playing a LOT of random vs matches, single player and coin launcher to try and randomly get it. Plus, there's no indication what achievements are needed to make certain stickers even available...
 * Better yet, stickers are expendable items. Seriously.

First-Person Shooter

 * The "Get Some Grub" achievement in Half-Life 2: Episode Two requires the player to kill all 333 Antlion grubs in the game. There are two grubs in particular that people tend to miss: One is inside a locker before entering the Antlion nest, and one is behind a wooden barricade after Other grubs are sometimes found on the ceiling or places the player can only pass through once with no way to get back.
 * And then there's the garden gnome you have to carry from start to finish in Half-Life 2, Episode Two.
 * The Monster Condo level in Doom II has a secret area that permanently closes up 30 seconds after the level starts. Guide Dang It...
 * It seems to be a tradition in the Metroid Prime games to have at least one obscure enemy that seems to exist for the sole purpose of preventing the player from getting 100% of the Logbook scans.
 * The worst is probably the Ice Shriekbat from the first game. Like all Shriekbats, these are difficult to spot and dive bomb Samus and explode as soon as soon as Samus gets near them. Unlike all other Shriekbats, they never respawn (except in the PAL version, supposedly). They also only appear in one room and are gone so quickly that you probably won't even know they were a unique creature. As some sort of cruel joke, their Logbook description suggests using the Thermal Visor to spot them, an item which you don't even have at that point in the game.
 * Worse yet for anyone following along with the Prima strategy guide. While it typically points out important new scans as you come across them, it doesn't even mention the Ice Shriekbats in the regular walkthrough.
 * When the game was rereleased in the Metroid Prime Trilogy compilation on the Wii, the ice shriekbats were respawning. Both a nice surprise to people who missed them the first time around and a nasty shock to the people who never expected to see them again.
 * The second game has a specific type of door that only appears in a boss fight, requiring you to turn away from the boss to scan it.
 * The third game has a specific type of Space Pirate (of which there are many almost indistinguishable variants) which only appears during a particularly difficult timed mission in which you fight a large number of Space Pirates while also having to deal with annoying ships that shoot at you from the distance.

Miscellaneous Games

 * Game Boy Camera could be a particularly terrible example of the trope. You could unlock special pictures with certain goals. Some would be like taking hundreds of pictures, trading tens of pictures to males AND females, or any other of random tasks.

MMORPGs

 * Billy vs. SNAKEMAN has secrets that nobody has found. The creator sometimes moves such secrets to less well hidden places.
 * Special note goes to the "Enough Already" Trophy. It's worth only 1 Awesome point (all other known trophies are worth a multiple of 5 Awesome points ), and is obtained by grinding your Season stat to its cap. Unless you're really lucky and willing to waste Fiction 500 grade cash, this means at least a month of dedicated grinding beyond the point more Seasons becomes anything more than a Bragging Rights Reward. And now you know why it's called "Enough Already".
 * City of Heroes used to play this trope straight, but now averts it. Many missions revolve around locating and interacting with several objects on the map. These "find the glowie" missions can grind to a halt if they have no time limit and the last one is hidden in an odd place. Eventually, to mitigate this frustration, the devs included a patch which causes the last glowie to show up on the map.
 * While Guild Wars doesn't have a true 100% Completion, it does have several infamous titles.
 * Each of the cartographer titles (one for each of three campaigns) requires you to explore every inch of terrain in the campaign. At first this doesn't sound so bad, since the local area map shows which sections you have not yet explored. But then you realize that there are some places, such as the edges of a zone, in which the visual cues on the map don't change once they've been explored. Many hours have been spent by completionists "scraping" the edges of every single zone in the game to get these titles.
 * Each campaign also contains the vanquisher title, which requires "vanquishing" (killing every enemy in an area while playing on hard mode) every zone in the campaign. Most enemies are either stationary or follow small, predictable paths, but the ones that don't can result in huge amounts of wasted time trying to find that Last Lousy Enemy in a zone with 200-300 enemies.
 * And then there is the Eye of the North expansion, which adds the Master of the North title. This combines the cartographer and vanquisher titles, along with doing quests and dungeons, into one title. This title is measured in generic "points" with no easy way of telling how far along you are on the already annoying cartographer titles unless you crack out a calculator and guidebook.

Platform Game

 * There are 1000 Lums in Rayman 2: The Great Escape, though "officially", there appear to be only 999 after a certain Cutscene in which the Big Bad eats one of them; the "last lousy Lum" is hidden in one of the other levels, although only on certain versions. There's a bit of Fridge Brilliance in its location too:
 * In the first Donkey Kong Country, the 101st percent could be obtained by reaching a Bonus Stage hidden inside another Bonus Stage. The first bonus stage is a matching game where you time your jumps to match three objects. You can only get to the second bonus stage by winning the worst item (a single banana), which causes a barrel to drop. You then have to grab that barrel and crash through the wall before the "celebration fanfare" is over. And you can only use Diddy, because he holds the barrel in front of his body (whereas DK holds it over his head, and you don't have enough time to throw it and then enter the resulting opening).
 * Also, that second bonus stage? You got one (and precisely one!!) chance to get it. If you failed to get in there the first time, you were screwed.
 * Donkey Kong Land has several, but the worst is probably in the "Spiky Tire Trail" level, in which to get to a bonus stage you have to jump down what looks like a bottomless pit, with no real indication that it's anything but a bottomless pit.
 * Similar to Donkey Kong Country, Crash Bandicoot 3: Warped had two levels that were accessed from within other levels - one of which was itself a hidden level. Fortunately, neither of these levels were necessary for Hundred Percent Completion, but only for 105% Completion.
 * Getting One Hundred Percent Completion in the Spyro the Dragon games can run into this. You'll inevitably spend hours searching a level for that one lousy jewel that you missed on the first playthrough.
 * And if you're going after the skill points in 3... Well, the Impossible Tower is called that for a good reason.
 * Luckily the second game adds in a feature that lets Sparx point out remaining gems for you...but the third game doesn't point this out until you beat a bonus level (he can do it before with the same button input, but a player unaware of this mechanic wouldn't know to try it before then.)
 * In Year of the Dragon area 'Dino Mines' there is an egg titled 'Leap of Faith'. You have to do just that to get the egg and gem that is with it. The problem? The problem with an egg like that is it'd be pretty easy to get to, so they put it behind a building. To get to it, you have to jump off of a cliff and fly around the rear of the building and land on the tiny area they give you. Good luck finding where you're supposed to jump though.
 * The "Last Lousy Jiggy" in the original Banjo-Kazooie is invariably considered the hardest in the game--it lies beneath the instadeath propeller blades of the ship in Rusty Bucket Bay. To get it, you need to complete a series of Timed Missions, one right after the other, involving slowing down propeller blades, tiptoing above bottomless pits, and swimming through Grimy Water all within a short timeframe to nab it.
 * Two other contenders would be the 'Mr Vile' Jiggy, in which the player has to beat a big red crocodile in an infamously hard mini-game. The other Last Lousy jiggy is easily missed, since it's up the top of the giant tree in the level Click Clock Wood, at an altitude that is only reachable while the player is transformed into a bee and that you never normally have to go to.
 * There's also the whole note issue. Click Clock World has four variations of the level, and you have to survive all 4 to get the hundred notes with the clincher being you have to start from 0 if you die.
 * On a similar note, several of the golden bananas in Donkey Kong 64 are incredibly frustrating to obtain. One of the more infamous is the mechanical fish puzzle in Gloomy Galleon. What's even worse is, if you put off getting that banana, it can trigger a Game Breaking Bug making the fish nearly impossible to beat without exploiting another glitch.
 * There's also one final battle arena crown that you can find, located in Hideout Helm. To get to it, you need to use Diddy Kong's barrel jetpack to fly to the top of the machine K Rool had been planning on using to blow up DK Island. There's no time to get it before you shut down the machine, people who don't know about it will probably not think to look up there because the key to the last boss battle is available, and it's entirely possible to get said final key without it (while you do need a certain number of crowns, it doesn't call for all of them).
 * Psychonauts: In addition to the Psi-Cards and Scavenger Hunt items in the overworld, you also have Brains in one specific area, Mental Cobwebs in the brains, and 1000+ Figments scattered throughout the 10 Mental Worlds--one of which you can never return to the overworld from.
 * In Mischief Makers, every level contains one Gold Gem. Once you've collected it for each level, there are still two more to collect.
 * Before getting that one, you'll need to break the world record in the 100m dash.
 * And defeat the main bosses without getting hit once.
 * In Kirby: Canvas Curse, each stage hides three gold medals, and each time trial offers three more for getting the three best times. There are three more medals, awarded for completing the hardest difficulty of each of the boss minigames. The boss minigames in the story were actually easier than the easy setting, and the hardest setting is damn near impossible.
 * Shadow the Hedgehog, Lost Impact, Hero mission. Defeat all 35 Artificial Chaos. Artificial Chaos are annoying enemies to begin with, but you'll almost invariably end up giving up and going to the finish line after about 10-20 minutes of being stuck on 34.
 * In Sonic Adventure 2, you will automatically get an A Rank if you collect all of the rings in a level. They don't make this easy, though.
 * Metal Harbor has a single ring sitting completely by itself in a place you wouldn't check unless you knew it was there.
 * Pumpkin Hill contains a pair of rings floating in an arbitrary, obscured part of the abyss around the level, away from everything else of importance. They're also below the point in the pit that registers as a death, so the player has to use a magnetic shield, which can only be obtained rarely by digging at random around the level, and pull out at the last possible second in the fall.
 * Some levels may have a ring or two placed outside normal reach just to make an A Rank impossible through that method. (Mad Space and Pyramid Cave are listed examples, discovered using Action Replay.)
 * The Gold Secrets in Tomb Raider: Legend. Also, there's many secret rooms in the original series that hold nothing significant, but nevertheless count towards your score.
 * Oh so many Last Lousy Monkeys in Ape Escape. Three that absolutely take the biscuit come from Ape Escape 3. In one level, you board an automatic platform. As you travel on it, monkeys swim in the anti-gravity tunnel it's moving through. You have to jump and swing at just the right second to catch them, you only get one shot per four-minute trip, and the little bastards move.
 * A phrase "Veni, Vidi, Vici" reminds a lot of players of the extremely difficult shiny thing to get in VVVVVV.
 * In nearly all of the Ratchet and Clank games, the skill points will be a mystery until you earn them (you didn't even know their names until you'd beaten the game once in the first game) and most of the challenge is figuring out what to do. However, there's almost always some skill point that's just plain hard, even if you know what to do. Some of them are almost Lost Forever in Challenge Mode, since the criteria for the point also sometimes set the bar higher. Particularly annoying in Size Matters, where the point requirement for a space minigame is set a lot higher in Challenge Mode...so much, in fact, that the best course of action may be to start a new game for 100% completion. The hoverboard race time trial skill points are also subject to this.
 * The "Everybody Dance Now" Skill Point from Tools of Destruction is this Up to Eleven. It involves getting tossing a Groovitron at every Enemy and NPC in the game to make them dance. Yes, ALL of them. The problem is, some enemies only appear in very specific places, and several can be Lost Forever, making them Last Lousy Points within a Last Lousy Point. Of particular note are your NPC allies Cronk, Zephyr and Talwyn, only available during, the MANY variants of Pirates, the Obsidian Enforcers on Planet Reepor (of which there are only 2) counting as separate ememies from normal Enforcers, remembering morphed Penguins also count and, by far the worst,  , who you need to throw a Groovitron at immidiatley after   and ONLY then!
 * Super Mario Bros examples:
 * Super Mario World has 96 exits all up. Most levels after the Green Hill Zone have two possible exits. The hardest to find is almost certainly the exit that leads to Soda Lake in Cheese Bridge Area: you have to fly under the exit gate (without going too low, of course)--going above it will end the level--and come to a landing on a platform behind it. It's not that hard for a skilled flyer, but you have to somehow figure it out or have a remarkably happy accident before you even know that's where it is. A Yoshi can make this particular jump easier, as it's only necessary to get behind the first goal, but you'll have to get him through the gauntlet first.
 * A second goal-behind-the-exit example is in Chocolate Island 3, made more suspicious by the higher level exit (it requires climbing a vine to reach). This time, you can't use a non-blue Yoshi to reach it, you have to fly quite a ways past the level goal to reach the secret gate. This time, the normal exit doesn't even lead anywhere.
 * Super Mario Sunshine to a ridiculous extent, thanks to the blue coins. Ten blue coins gets you one Shine Sprite, and there are 240 of the damn things you have to find if you want 100% completion. A few are in plain sight, but the majority of them are hidden in extremely non-intuitive locations. Enjoy spraying every object in each of the multiple variations of the many huge levels of the game. Never mind, there's no enjoyment in that. Make a checklist or use a walkthrough if you value your sanity. Or just skip out on the whole 100% thing.
 * Super Mario Galaxy 2 does it literally. The absolute final star, only available after collecting all 241 previous stars, amassing 9999 star bits, and beating the final boss twice; is without question the hardest level since Super Mario Bros.: The Lost Levels (and arguably harder than even that). It's an even harder version of Grandmaster Galaxy (the hardest level in the game) with daredevil comet in effect (meaning Mario has only one hitpoint) and no checkpoints. Six sections, three miserable Boomerang Bros, and zero mercy.
 * In One Hundred And Two Dalmatians, each level has 100 bones. Many of them are just lying around, so exploring the dungeon will find them (in fact, it's hard/impossible to get no bones at all). Some need to be sniffed out and dug up. Some are gotten by killing enemies. Some by completing sidequests. And then, in the first level, are some bones that can only be gotten by  No hints are given that this is something you might want to do.
 * Most of the in Braid, the existence of which is never mentioned in the game. Special mention goes to Cloud Bridge, in which you have to wait for a cloud to slowly move left for at least two hours to reach a secret area. And before you think you can just leave the game running for two hours: you need to jump on the cloud at about the 50 minute mark and then continue waiting.

Puzzle Game

 * In Portal, finding each and EVERY one of those stupid cameras for an achievement takes forever.
 * And with the update that introduces the radios and the interference as a teaser for Portal 2, finding each and EVERY one of those stupid radios AND figuring out where you have to take each to get their respective interferences, all for another achievement.
 * Super Scribblenauts: The final Starite is found by using the time machine. There's a chance that the time machine will take you to a Nostalgia Level with the final Starite in it.

Rhythm Game

 * The last lousy achievement in Lego Rock Band counts. Most of them are attainable at easier skill levels; finish the game, play the 30-song endless setlist, even 100% with a full band isn't bad because you can play any difficulty. Then there's one where you need to get 100% on the solo in The Final Countdown on Expert. Even then, veterans still might be confident until they actually see said solo. Cue zig-zags.
 * There is exactly ONE (and only one) way to make it easier, and that's to abuse the hell out of the shredboard solo pull-off rules added in Rock Band 2 (which NEVER get mentioned in the tutorials or manual). When using the shredboard in a solo, you are actually allowed (in Rock Band 2, games using its engine, and Rock Band 3) to pull off from a lower fret to a higher fret.
 * In DJMAX Portable 2, the Last Lousy Mission isn't "Enter the Pentavision", the last mission in the game. It's "Just 1%", a mission which, on top of having to chain three Fevers on each song, requires you to clear each song without the "MAX 1%" judgment, yet you're allowed to miss notes.
 * Dance Dance Revolution Extreme US had the Last Lousy Song "Memories", which was only accessible via a code released two years after the game's release.
 * DDRMAX US had "Drop The Bomb(System SF Mix)", which had to be unlocked either by playing 500 songs or completing the long and hard Hardcore Oni Course.
 * Rhythm Rally II in Rhythm Heaven.
 * Most of the Remixes count, but Moai Doo-wop 2 and the aforementioned Rhythm Rally 2 have driven many a completionist utterly insane.

Role Playing Game

 * In later Wild Arms games, there's a Bonus Boss you can only fight if you've opened every single treasure chest in the game. Heaven help you if you've missed one, and now have to painstakingly search every single spot you've ever been.
 * Filling out 100% of the world map in 3 and Alter Code F is mostly just a little tedious busywork, but once the majority of the map is filled out and the remaining blank spots blend in with the rest of the map or are hidden by the edges of continents...
 * For Hundred Percent Completion of the compendium of Persona 3: FES, you need to unlock Orpheus Telos and fuse him. However, to actually get the ability to fuse him is that you must have every single social link maxed by the end of the game. It's nigh-impossible to complete this task without a guide: The game takes place over a typical school year with interruptions, and specific social links are only available on conflicting days -- doubly so for the "girlfriend" social links, which break apart if you try to do multiples at once. In the original game, this involved spending every single day in the game in a very specific order (and intentionally getting one character angry at you); in the expansion, you have a few spare days at the end, but still cannot deviate from a very specific plan.
 * In Pokémon--that is to say, every single main series Pokémon game--there are one or two special Legendary Pokémon which are not available normally. These are usually obtained by storyline events, and with the One Game for The Price of Two mechanic, you usually have to trade for the last one. That's not the Last Lousy Point. The Last Lousy Point for Pokémon games are the Ultimate Legendaries - those Pokémon you cannot get without outside help, usually obtained via a special Nintendo event (or, for the more opportunistic, using a cheat device). They may show up on the GTS (barring the ribbon holding mons that can't be traded) but they go FAST when it isn't someone just looking to store it there by asking for something like a Level 9 Reshiram that they can't ever get.
 * As of the fifth generation, there are now twelve of them, many of which won't be given away during the time after Black & White came out. Hope you didn't trade in your old Pokémon games to get the new ones, or you'll never be able to get hold of them.
 * The first generation featured four Pokémon (Gengar, Machamp, Golem, Alakazam) that could only be obtained by trading - this was done to encourage One Game for The Price of Two.
 * Many Pokemon are exclusive only to one half of the One Game for The Price of Two, and you can only get them via trading. Some will at least appear used by NPC trainers to allow completion of the Pokedex, but others, like Braviary in Gen V, don't. There's also usually only one of the two legendary mascots of each gen available in one game unless you're playing the "third game", where both are usually available, or getting lucky with a Wifi event.
 * Braviary is used by exactly one trainer in the game,, so while those with only Black version can't catch it themselves, they can at least see it for the Pokédex and request it on the GTS. The real problem is its pre-evolution, Rufflet, and its Black version counterpart, Mandibuzz, who, like Chimecho mentioned below, are one of the few non-legendary Pokémon never to be used by any in-game trainers in its generation. If you're playing Black and request a Braviary, you can breed for a Rufflet, but until then, you can't even request a Rufflet.
 * Every game since has introduced new Pokémon that can only be obtained by trading them while they are holding a specific item (Kingdra, Steelix, etc). Said item naturally could only be found one time at one place once in the game (however, in later games, some trade-item evolution Pokémon like Steelix are available in the wild).
 * The real Last Lousy Pokémon is a normal Pokémon, Feebas. It's found on six randomly generated tiles in a gigantic pool of water, and thanks to the random encounter system there is no guarantee that you haven't found its tile already but didn't notice.
 * The evolution of Feebas, Milotic, is far worse. Without looking at a guide (or the internet, to be fair), it would be difficult to guess that the slimy bug-eyed brown Feebas would evolve into the beautiful brightly-colored serpent-like Milotic. Furthermore the only way to cause the evolution is to make it beautiful by feeding it candies. And in order to get enough Beauty, it usually requires a Special Attack-boosting nature, decent to high quality Pokéblocks, and semi rare berries.
 * Fortunately, Gen V made things easier. You can get Milotic by trading Feebas holding a Prism Scale. Or you can occasionally catch a Milotic outright in the rippling water off Route 1 after you have Surf and the National Dex.
 * Even Game Freak realized this was too much work. In Heart Gold/Soul Silver, due to the removal of Poffin making, Feebas could be evolved by getting it massaged. Of course, you can only do this once a day, for just one hour a day, and if you miss it, you've gotta wait 'til tomorrow. Possibly as an apology, in Black & White, you can evolve your Feebas by trading it with an item attached, like many other Pokémon.
 * The Socialization Bonus requirement for getting Spiritomb is talking to people 32 times in the Underground. Add to the fact that one needs to leave and reenter the main part of the Underground to make repeated conversations count and it's a fairly tedious process for people who don't have anywhere near that many friends to play with.
 * The only other way to get a Spiritomb lies within the Pokéwalker (a Pedometer with a Pokémon catching minigame built in) that was sold with Heart Gold/Soul Silver. Naturally this was still mind-numbingly hard, as you had to earn 100,000 watts to get the route Spiritomb's could be found on. At twenty steps a watt, you had to take two million steps before you unlocked the route. At least this part was cumulative, once you got the route where you could get a Spiritomb, you still had to walk over 10,000 steps in a single day to have any sort of chance of actually seeing said Spiritomb, and even then the chances were still very low.
 * All this just makes many a player glad they're not tasked to find the 1 in 8,000+ odds of seeing the shiny form of each Pokémon. It's already nigh impossible without access to every game since at least Generation III in which all legendaries and Ultimate Legendaries have been caught.
 * Speaking of Pokémon: let's say two friends set out to max out Generation I. One gets Red, the other Blue. They use an exploit at the beginning to have all 3 starters, and after that they pick different rewards when opted (the fossils and the dojo Pokémon). They trade every 'mon the other couldn't have on his/her own. How many would they end up with? That's right, 149 out of 150, the Last Lousy 'Mon being the third form of Eevee.
 * That's where Pokemon Yellow comes in. Or the Pokemon Stadium transfer/start-over trick.
 * Chimecho in the third generation games. 1% Chance of finding it on Mt. Pyre, which you're bound to be on ONLY for the plot . Thankfully, Chingling are easily found in Generation 4.
 * Another third gen problem is Skitty. It's found in one area of one route, but at only 2% chance of finding it, good luck and lots of patience are required. And in Gen IV, you had to wait for a swarm after you beat the game. It explains the fact that so few Skitty are found on the GTS even now.
 * In Final Fantasy X-2, If you miss talking to the Moogle-Suit person towards the beginning, while pursuing, you'll lose 100% completion.
 * Hell, that game is full of those. Pick the wrong side? Can't get 100%, sorry. Didn't do the exact right sequence of things before AND during the investigation? Can't get 100%. Saved the Zanarkand Ruins mission for last in the last act? My, that certainly won't do. Didn't wait for the whistle? Haha! You loser! Touched the controller during the Exposition Break, or even skipped a cutscene? Might as well start over from the beginning. Fractured your skull against a wall? Oh, you'll never make it as an FFX-2 player if your head explodes.
 * The game is fortunately kind enough to provide a New Game Plus. And the percentage points gained from faction sidequests don't overlap, so by the virtue of New Game Plus you can reach an onscreen 100% without ever having to beat the nigh-impossible Bonus Bosses.
 * And let's not forget the Dresspheres, and the Garment Grids - the best Dressphere in the game, the Mascot, is unlocked by talking to the innkeeper. In all five chapters. As for the Garment Grids, the last one you get gives you the intrinsic ability to use a Game Breaker ability - if you never run from a battle during the entire game. It is also unlocked by viewing every possible enemy in its Oversoul mode - an annoying challenge that virtually requires fleeing from enemies regularly (thank goodness the Grid and its Game Breaker carries over into a New Game Plus). Bottom line - Only about 40% of the game is completed if you just run through, and that other 60% is VERY easy to miss something out from, so if you want everything, buy a strategy guide (or better yet, check gamefaqs.com), or get ready to reset constantly.
 * Trying to get the Monster Collection fragment in Final Fantasy XIII-2 is particularly painful, as it requires you to defeat every enemy in the game, some of which are Bonus Bosses capable of stomping you and many rare monsters that pretty much require a guide to even find.
 * The game is made of this. Several quest items are hidden in places you'd never think to look (the upper corner of a room, near the bottom of a pit, etc), one fragment requires hours of playing slots, there's the quizzes with no answers provided in-game...
 * Avalon Code has one of these for most individual maps. To unlock the full point value of a non-dungeon map area, and sometimes unlock bonuses, you need to examine every search point. Some of them are obvious, but some are absurdly well-hidden. To top it off, if you try guessing in an area where you can fight, you'll try to initiate a Judgment Link if you're wrong about where they are, wasting time and making the whole process of combing the map take even longer.
 * In the Tales Series, there is a considerable amount of this. Oh, there's the usual 100% items, monsters, weapons, armor, etc. But then there are the skits. The optional, story or even completion level dependent cutscenes that pop up. They can be easy to miss, since they don't instantly start, and only give that option after a few seconds pause. If your hurrying along, you can easily miss them. Some are only available in ONE specific room after ONE specific event. Also, they usually have their own completion counter, and when some skits only show up on certain story paths, of which there can be more than one, you have to play through the game more than once.
 * For example Tales of Symphonia must be completed three different times to even have a chance at 100%.
 * If going for 100% completion including the skits, you're going to have to play the game 8 times, as every character has their own skit if you pick their ending.
 * Even worse, to get 100% on the Collectors Book you have to get Zelos as your best friend. The guy barely trusts you when he joins the team and takes a lot to win over. Even if you do everything right it may still take more than one playthrough to get him. Oh, and some of the choices that make him like you more have a negative effect on other people (like the equally difficult, Presea, who fortunately doesn't give you anything for the Collector's Book).
 * And just as bad is Genis' strongest weapon, One World. To get it you need to beat 99.9% of the game. See, after you open the door to the final boss there's a scene and a teleporter to the boss. Instead of fighting the boss, you need to leave the room and go play a minigame that offered mundane prizes before now (you're not actually told the prize is better now). The minigame is very difficult. If you win, you get the Infinity Plus One Kendama. This is likely to be the last item you get in the Collector's Book.
 * In Tales of the Abyss those last points will probably come from the Din's Shop weapons, seeing as the game never tells you exactly what you can find there, or how many points they cost (with Dymlos, the most expensive weapon in the shop, costing 160 points). And you only get a measly one or two points for most of items you bring in, and only certain items give points towards each category. There's a damn good reason Game FAQs has a whole guide dedicated to this shop.
 * The Last Lousy Viviosaurs in Fossil Fighters are a quintet of baby birds, one for each element (minus Legendary). Their abilities aren't generally that special, but the only way to get them? To get every other viviosaur in the game and max out their levels. That'll keep you busy for a while...
 * The Last Lousy Monster in Monster Rancher Advance 2 is Octochrome. The only way to get it is by raising an Octopee monster to S-rank, and then waiting to be randomly attacked by it. If you beat it, you get a code for it. The problem? Thanks to a glitch, it's totally unobtainable. Well, unless you break out the cheat device.
 * In The World Ends With You there are many things to buy, monsters to beat (on several difficulties each no less) and pins to collect and master. If you miss something along the way, never fear. Completion of the game allows you to return to any point in the game and redo any challenge or find anything you may have missed. The catch? There is one event earned pin that will only be given out ONCE. And ONLY once. If you happen to sell it before mastering it for some reason then you have no way of ever getting it back and then the perfect game is, in fact, impossible unless you feel like going back and starting all over again.
 * The Baten Kaitos games love this, as part of the incredibly sadistic Hundred Percent Completion they offer. In the first one, the Last Lousy Magnus is usually either the Frost Cap (dropped by one enemy in the Trail of Souls, which you visit once), the Splendid Hair (age Shampoo for 336 hours real-time), or the Maskless Mizuti Shots (two pictures taken of one of your characers while in the middle of a very specific boss battle, one of which has a minuscule chance of appearing). All with an extra helping of Guide Dang It and Lost Forever, as none of these are even hinted at in game and many of them are only available once.
 * The second game was a little better about this, although several Magnus could easily be Lost Forever and some others required obscenely long aging times or convoluted magnus mix recipes.
 * Xenoblade has the Last Lousy Collectible for each area. Made worse by the fact collectibles are scattered everywhere and respawn, but you don't know what one is until you pick it up, making it an exercise in luck and frustration. This goes double if you miss one from an area you can't return to - you can trade for them or find them by luck at a certain area, but this takes either a guide (for the former) or plain old orders of magnitude more time and luck (for the latter).

Stealth Based Game

 * The Thief games require you to collect a percentage of the treasure on each level depending on difficulty level. On the highest levels, you can expect to spend many a frustrating hour looking for those elusive last few bits.

Third-Person Shooter

 * In Bullet Witch, there are five different difficulty levels: Easy, Normal, Hard, Chaos and Hell. You can earn Chaos mode by beating Hard, and you get Hell by beating Chaos. Beating the game 5 times for all the achievements is bad enough, but it gets even worse once you realize that while beating Chaos mode is worth 250 points, beating Hell mode is only worth

Wide Open Sandbox

 * The last yearbook photo in Bully, which you can't see until you've taken the photo, so you don't know who you're looking for.
 * And even if you do know, you're not sure which person they are, and so you still have to take photos of EVERYONE to get it.
 * Yakuza 2 (Ryu ga Gotoku) has a big Completion list that keeps track of just about everything you can possibly do in the game. If you want to fill it, you have to get perfect scores on every golf, baseball, and bowling mini-game, plus earn a ridiculously large number of chips, medals, and tokens in the various casinos and pachinko parlors, etc. etc. etc. As above, there's no real reason to do any of this, but it's so comforting to know you have the option.
 * Just Cause 2, not because of a particularly infuriating collectible or mission, but because there are so many damn missions, locations, and collectibles in the game that it's practically impossible to complete the game 100% without resorting to guides or 3rd party mod tools (in the case of the PC version). Gamers can spend dozens of hours (after having already spent 100+ hours getting everything else) looking for that last collectible hidden in a completely nondescript nook in the game's enormous world.
 * It says something about a game if, instead of "Last Lousy Percent" it has "Last Lousy Hundredth of a Percent"
 * That's why the completion achievement only requires 75% completion.
 * Red Dead Redemption can be this, both the main game and Red Dead Redemption Undead Nightmare. Capturing wanted criminals counts toward Hundred Percent Completion (in the main-game) and saving missing people in the expansion. The problem? You have to get all of the criminals for each city (that put up Wanted-posters), and all of the missing people for the towns in Undead Nightmare (Thankfully, there are about two to three that do so). They also repeat, so you can capture one guy, but if that guy is the "final one", it repeats. And if you don't know this... Well.
 * GTA: Chinatown Wars nicely averts this (mostly) for members of the Rockstar Games Social Club who register their copy with Rockstar (Friend Code/PSN Username/Etc...) by supplying up-to-the-minute maps that reveal the location of collectables. The only exceptions are the Lions of Fo, the locations of which are randomly chosen from a set of points indicated by swirling winds.
 * If you use the cheat codes and then save in Grand Theft Auto Vice City, one of the hidden packages will disappear permanently.
 * Endless Ocean is a very hard game to get the Last Lousy Point in. Many creatures appear only in certain areas and some only appear in certain times of day. The seasonal species take longer, making the player wait for the correct season to trigger their appearance. But by far the most annoying are those that only appear under glows, twinkling lights that appear on rocks,coral or the seabed, like frogfish and sea slugs. And then there are the treasures that appear under glows. Some that double as Plot Coupons appear in specific places, but others are random and can appear anywhere on the map. There are areas where there's a higher likelyhood of treasures appearing, like Hidden Lake, but it's still frustrating trying to get every last one. Oh, and there are repeats; you can find one you've already got. The sequel, Endless Ocean Blue World makes things even worse due to it having several dive locations around the world and a lot more ground to cover. The findable coins will appear in specific places, but the treasures and salvage are again random and repeats happen quite often. Certain legenday animals require tasks to be completed, and when photography is involved, it's quite difficult to produce photos the game will return A's on...even seemingly good ones often return C or B grades instead.

Other

 * Take a look at the list of achievements for a given game on Steam. The ones with the lowest achieved percentages will be the ones which fit this trope.
 * TrueAchievements.com has a system for rating X Box 360 achievements on their difficulty: Take the total number of gamers tracked who have the game (defined as having at least one achievement for that game), divide by the number of gamers who have that achievement, then take the square root to get the TAScore. The easiest achievements have a TAScore closer to 1.00. Once you get past 5.00 or so, you're in Last Lousy Point territory.