Underused Game Mechanic

All games have mechanics — predefined methods that the players use to interact with the game world. Some of them are well-received, others not so much. And then there are mechanics that are cool and innovative... but only come up once or twice in play and are then never used again in the game or even in the entire series. This can happen for a variety of reasons — maybe it had to be cut out due to production problems, or the designers didn't realize it would be popular, or just found that it simply did not work in practice and cut most of it out. The end result is that the players want more of it, and don't get any.

Supertrope of Useless Useful Spell, Useless Useful Stealth, and Useless Useful Non-Combat Abilities.

Contrast Scrappy Mechanic. Compare They Wasted a Perfectly Good Plot.


Examples:

    open/close all folders 

    Action-Adventure 
  • Remember Me has only a few memory-altering minigames, which is particularly egregious in that these puzzles were a major selling point for the game during the pre-release promotion.
  • Jak 3: Wastelander: One new feature that many fans felt was disappointing was the implementation of Jak's new Dark Eco ability of Invisibility. Aside from an once-visited volcano level, it could only be used at the Monk's Precursor Temple monastery, thus meaning any use of it this for any stealth based tactics (or for that matter any sort of stealth-based missions) outside that location is denied to players. Granted while there is an unlockable ability to turn invisible by pressing the triangle button in Dark Jak form, but that only becomes available after completing the game (though it is somewhat subverted if someone buys it from the Secrets menu and then starts a New Game on Hero Mode).

    Driving Game 
  • F-Zero AX is the only game in the series to increase the number of laps based on the track length, resulting especially in the very short Aeropolis: Screw Drive and Mute City: Sonic Oval tracks having decently long course times with 6 and 8 laps, respectively. In GX, these tracks are practically over as soon as they start, due to using the usual three-lap rule.
  • Wangan Midnight Maximum Tune:
    • In Maximum Tune 2, if all players in a 2- or 3-player VS match on a setup with at least one open cabinet hold down the red button during course loading, additional players cannot join in on the race. This was unfortunately not kept from Maximum Tune 3 onwards, meaning that an intense <4-player battle could be suddenly interrupted by a cardless player and there's nothing that can be done to prevent it short of forcing said player to decline challenging.
    • In Maximum Tune 3, when racing in a Tokyo sub-area or Hakone in VS, players can vote on the starting ramp. This was removed in 3DX onwards in favor of randomized ramp selection.
    • In Maximum Tune 5, Extreme Versus Battle mode allows the players to drive the cars in reverse, oncoming traffic configurations. However, due to Interface Screw issues, this was deleted from 5DX.

    Fighting Game 
  • Super Smash Bros.:
    • Melee:
      • This game stands out by having the most "advanced techniques" in the franchise, the most prominent of which is wavedashing, a slightly Good Bad Bug movement method that defines the metagame to this day. Wavedashing and the like were removed in Brawl onwards to streamline gameplay; nobody can agree on if this was a good idea or not.
      • This is the last game in the series to have individual "Break the Targets" levels for every fighter. Brawl reduces the mode to just five stages of increasing difficulty with a focus on item usage, and 3DS/Wii U replaces it entirely with Target Blast.
    • Brawl:
      • This game introduces stickers as a counterpart to trophies, depicting lesser-known characters and objects from Nintendo's franchises. These stickers can be put on a fighter's "trophy stand" via an Inventory Management Puzzle, providing stat boosts or special benefits such as starting items. However, this feature is exclusive to the Subspace Emissary story mode, so stickers are useless when it comes to multiplayer. 3DS/Wii U also includes stat editing for fighters (and it works in every mode), but it's done with a simple three-slot system of equips, lacking the unique appearances of stickers, which did not make the cut.
      • Gliding is a rather peculiar technique that's only limited to a whopping three characters. It was dropped in the fourth generation.
    • 3DS/Wii U
      • The Mii Fighters. It is at its core a great idea, offering the possibility to create your own smasher, but in the game itself it is very difficult to really make the character you want as its characteristics and even cosmetic elements are unlocked via very frustrating Random Drops. To add to this, the Mii Fighters aren't even available to play online in "With Anyone" mode, needlessly limiting their interest for hardcore players.
      • The Custom Moves are also given at random, and are not available online with anyone either, though Mii characters and Palutena (who have radically different specials) have all of them available at the start. The DLC characters don't even have Custom Moves, which make one question if Nintendo itself completely dropped the idea.

    Hack-and-Slash 
  • Dynasty Warriors 6 introduced new mechanics to the series such as grab attacks note , dodging, the need to break down doors to bases before entering them, on-map duels, and attacks after winning weapon locks. However, due to the poor reception of DW6 (mostly due to the Renbu battle system, cut characters, etc.), they decided to scrap all of these features come DW7.

    Platform Game 
  • Donkey Kong Country 3 introduces Dixie's ability to lob Kiddy Kong into the air, smash into the ground, and potentially reveal secrets. Most players use it once in the first level only to almost never use it again.
  • Kirby: Squeak Squad features an ability mixing system where you can combined two ability bubbles to make a new ability. While this usually creates a preexisting ability, there are a few special abilities that can be made with certain combinations. The problem is that there are only five of these (not counting mixing two Sleeps to get Ghost), you don't get the scrolls that let you create them until the last third of the game, and they're just elemental versions of Sword and Bomb, not providing much extra combat capability. It's basically a watered-down version of Kirby 64: The Crystal Shards' ability combination system.
  • Ratchet & Clank:
    • In Ratchet & Clank: Going Commando, one of the 3 new robots that can assist Clank is the Lifterbot, which can lift up blocks for Clank. Or rather, it can lift up ONE block for Clank, and then never be used again.
    • In Ratchet & Clank: Up Your Arsenal, the Warp Pad is a gadget that lets you place a location to warp to at select points. There are 2 of these select points in the entirety of the game, which both appear in the same level. Even better, one of the sections can also be completed using the Charge Boots instead.
  • In Sheep, Dog 'n' Wolf, we have a mechanic where you can keep running in the air for a few seconds after running off a cliff (in a typical Looney Tunes fashion). This mechanic isn't put to any practical use anywhere outside the tutorial.
  • Super Mario Bros.:
    • Super Mario Bros. 3's Goomba's Shoe. Using it was the only way Mario could defy Spikes of Doom and enemies with them, and it made World 5-3 a memorable level... and only 5-3, because the shoe isn't found anywhere else, can't be taken out of the level, and proceeded to disappear from the series without a trace. The GBA version added an e-Reader level that uses Goomba's Shoe, but it wouldn't properly return until Super Mario Maker, where the shoe and variations of it can be added to levels. To a lesser extent, there's the Hammer Bros. Suit; beloved for being a Game Breaker, but it has yet to return to the series, though it can at least be used in any level.
    • The Blue Shell in New Super Mario Bros. 1 is fun to use due to its defensive capabilities and shell slide (also, nice to have the Blue Shell not be the object of fear and hatred for a change), but it appears far too infrequently (while there is an enemy that drops it, said enemy only appears in a multiplayer stage), and none of the stages are really built around using it. It's also one of the few powerups that hasn't appeared in any other New series games, though the Penguin Suit is a Suspiciously Similar Substitute.
    • Yoshi's use in Super Mario Sunshine is fairly limited. He has a host of abilities, but the only one that gets any real use is spraying juice on blockades. His flutter jump is outclassed by the FLUDD nozzles, and turning enemies into platforms is only utilized in a single mission, which also makes changing Yoshi's color (which creates different platform behaviors) unnecessary outside of another single mission. He doesn't even show up much, only being needed for about one episode per level (sometimes only to open up a secret stage) and some Delfino Plaza secrets.
    • Super Mario Galaxy has the Red Stars that give Mario the ability to fly. Too bad there are only two in the whole game: one in the Gateway Galaxy in a Purple Coins mission and the other in the Comet Observatory for reaching a few 1-Up Mushrooms. It's only obtained at the point where you can beat the game so it's largely pointless. Worse is that a spin attack from Flying Mario can actually pull nearby purple coins toward you. If that's not reason enough why they should have included the powerup in other missions, just imagine using it in a boss battle. They don't even return in the Mission-Pack Sequel Super Mario Galaxy 2.
  • Crash Bandicoot: The Wrath of Cortex introduced Invisibility Boxes. There is three of them in the entire game, two of them in the same level. Especially jarring when considering the amount of crates in this game.

    Puzzle Game 
  • Ace Attorney:
    • Gyakuten Kenji 2. Fingerprinting is back! And it's used exactly once.
    • Professor Layton vs. Ace Attorney: Puzzles with Contradictions. The concept in and of itself is an amazing new twist on the formulas of both original series, but it is only used once in the entire game, albeit at a critical point. Also, you are again able to present profiles in cross examinations, but it's never used.
    • The DLC case from Phoenix Wright: Ace Attorney – Dual Destinies boasts the comeback of the forensic investigation we saw back in Rise from the Ashes and in Apollo Justice... except it was simplified as heck. Luminol tests now need a single spray on the right area to reveal the bloodstain (as opposed to the multiple touches you had to do before), and the fingerprint search and analysis is done for you by another character while you're in court.
    • The first case of Apollo Justice: Ace Attorney features a 3D diagram of the crime scene in the first case that you can manipulate in the courtroom to see possible contradictions. Despite being potentially useful, it was sadly not used after this particular case.
  • Tetris:
    • The Tetris: The Grand Master series introduced Initial Rotation System, which lets you pre-rotate the next piece by holding down the button corresponding to your desired rotation direction in the small delay between when a piece locks and when the next piece spawns. Tetris: The Grand Master 3 introduces an offshoot of this called Initial Hold System, which lets you swap out the next piece with whatever is your current Hold piece immedately once said next piece spawns. Both features are extremely useful at high gravity but have not seen wide adaptation to main Tetris games, not even to such games that do feature maximum drop speed such as Tetris DS.
    • Tetris: The Grand Master 2 introduces "sonic drop", where you can quick-drop a piece but without locking it, making filling in overhangs much faster. (To compare, a "hard drop" instant-drops the piece and locks it in place immediately.) It has unfortunately never been used in a main Tetris game; you have to use the also-non-locking-but-slower soft drop instead.
    • Double/co-op mode, where two players share one extra-wide field, can be a fun exercise for friends who like playing Tetris together, but very few Tetris games have it (Tengen's unlicensed NES port of Atari Tetris, Tetris: The Grand Master 2 PLUS, and Tetris Kiwamemichi which notably allows four players to use the same playfield at once).
    • Until the late 90s, "lock delay" (pieces having a delay between when they touch down and when they become locked in place) was mostly exclusive to Tetris games by SEGA and Jaleco; the first game to include it is SEGA's 1988 Tetris arcade game. Nintendo's NES, non-Color Game Boy, and SNES Tetris games as well as Atari's arcade Tetris game and accompanying NES port, all of which are more well-known in the West, don't include lock delay despite being a good way to curb frustration at higher drop speeds.

    Real-Time Strategy 
  • WarCraft
    • Warcraft III's "Spirits of Ashenvale" mission had a unique mechanic where it was possible to obtain lumber from destroying Night Elf tree structures, yet it's seen nowhere else throughout the game. Even though 3,000 lumber coming from Trees of Life sounds way overpowered, it makes sense in context when you realize that Night Elf structures that absorb the Wisp worker are technically trees.
    • Sea warfare, which was a major component of Warcraft II, took a huge backseat by the time Warcraft III came around. It didn't exist in the original Warcraft III: Reign of Chaos game, and while the Warcraft III: Frozen Throne expansion brought back naval combat ships, they were still limited to only being in the single-player campaign, and only for certain missions since it wasn't possible to build shipyards. The player could only purchase ships from pre-placed shipyards.
    • For some odd reason, the player is never able to make Chimaeras in the Night Elf campaign for Reign of Chaos.

    RPG — Eastern 
  • City building in Dark Cloud and Dark Chronicle. While Dark Cloud 2/Dark Chronicle does allow more freedom in building the towns than the first (wherein you simply placed buildings), in practice you were limited with having to fulfill certain conditions, many of which had to be done in very specific ways with little room for deviation. The second game gives you maps with extra restrictions, which would have made the player think more creatively. However, the city-building is in practice more of a Sidetracked by the Gold Saucer.
  • Final Fantasy VI introduces the Limit Break system to the series, known here as a "Desperation Attack". Unfortunately they only trigger when a character uses the Attack command at low health 1/16th of the time, and never in the first twenty-five seconds of combat. Because of these restrictions one can go through multiple playthroughs and never once trigger a Desperation Attack.
  • Shadow Hearts:
    • A Malice mechanic is alluded to in Shadow Hearts Covenant, but, like its apparent plot significance, never comes up in-game.
    • From The New World explains "Will" as the good counterpart to Malice, and it's explained that too much Will is as bad as too much Malice. But there is no gameplay mechanic about Will or Malice.
    • The vampires mechanics in Covenant and From The New World can feel this way too, if only because of how little the game mentions them or how utilizing it often uses rare and/or expensive in-game items.
  • Pokémon:
    • Gen 2:
      • Gold and Silver played around with the idea of being allowed to journey in multiple directions after departing from Ecruteak City. However, the poor leveling-curve that resulted in low-level Pokémon in whichever side the player chose to save for later ended up doing more harm than good.
      • The post-game content of Gold and Silver where the player heads off to Kanto to see that region's timeline updated several years after Red's adventure was a great way to extend the Pokémon endgame. Yet apart from the HeartGold and SoulSilver remakes, this was the only generation to do such an extension.
    • Gen 3: The Vs. Seeker that was introduced in FireRed and LeafGreen was a great, and simple, item to use that would allow players to re-battle any trainer they've already come across, and possibly battle against new high-level teams. It made leveling up the player team's Pokémon much easier, and feel like less of a chore. Yet after Diamond, Pearl, Platinum, this Key Item is dropped completely.
    • Gen 4:
      • HeartGold and SoulSilver, in order to make up for the lack of the Pokétch, fills the bottom screen with shortcuts to menu options and an interact button. There's one button that toggles your Running Shoes so that you can run without holding down the B button. Since there's few times when running is a bad thing, this is very useful. However, as later games lessened the use of the touch screen, this toggling feature has never returned.
      • HeartGold and SoulSilver had quite a few mechanics like this. The Berry Pots (which let you grow berries on the go, instead of planting them in a single spot and having to remember where they are) are exclusive to it, and the GB Sounds key item (letting you listen to the soundtrack of the original games by turning it on) doesn't have an equivalent in the Ruby and Sapphire remakes two gens later. By far the biggest, though, is the following Pokémon feature. It's very much cosmetic, but fans enjoy it for adding a lot of flavor, and they eagerly await its return.
    • Gen 5:
      • Pokémon Black and White introduced two new types of battles, Triple Battles and Rotation Battles. Triple Battles, as the name suggests, were a step up from Double Battles, where each side had three Pokémon active at once; unlike Double Battles, positioning mattered, since Pokémon on one end generally couldn't do anything to the Pokémon on the other end, although you could switch a Pokémon on the end with the one in the middle, adding an extra layer of strategy. Rotation Battles were similar in that each side had three Pokémon out, but only one was active at any given time; in addition to attacking or using items, each side could rotate their active Pokémon out as a free action, making Rotation Battles a major mind game. While neither battle variant ever had all that many NPCs that participated in them, Pokémon Sun and Moon dropped focus on them completely, isolating them to Player Versus Player battles.
    • Gen 6:
      • Pokémon X and Y introduces a new kind of battle called Inverse Battles that inverts the series' Elemental Rock-Paper-Scissors, making it so that Fire is strong against Water instead of resisted, Ghost can now hit Normal, etc. While this is a very interesting new take that drastically changes how almost every Pokémon functions and breathes new life into otherwise horrible ones, it can only be used against one optional NPC and there is almost no Player Versus Player support for it. Omega Ruby and Alpha Sapphire did expand their availability somewhat by letting players set their Secret Bases to use Inverse Battles, but beyond that, they were still just as limited as they were in X and Y. Pokémon Sun and Moon finally dropped them completely.
      • X and Y also introduced another kind of gimmick battle, Sky Battles. Like the name suggests, Sky Battles take place high in the air, limiting the participants to using only Pokémon that are Flying-types or have the Levitate ability and moves that don't involve some kind of terrain. While there were more Sky Battles than Inverse Battles, they were still all optional and not eligible for PvP matches. Furthermore, it wasn't very intuitive which Pokémon would actually be eligible to participate, since even being a Flying-type or having Levitate wasn't enough to guarantee anything; it turns out that if the Pokémon's idle animation had it standing or sitting on the ground, it was disqualified. Apparently having two sets of idle animations for a given species wasn't an option, because a number of species got unpopular changes to their previous idle poses to make them eligible for Sky Battles; unfortunately, while Sky Battles never made it out of their game of origin, the idle pose changes have persisted for much longer.
      • Mega Evolution was a big selling point for Gen 6 as a whole, and about half of the game's plot is spent obsessing over it. Despite this, there's a decent chance you won't end up using a Mega Evolving Pokémon on your final team. Only two Mega Stones are given to you outright (your Kanto starter and Lucario), and there are a grand total of four other stones that you can get in the main game. The other seventeen or so can be gotten in the post-game, which is infamously short by Pokémon standards. Omega Ruby and Alpha Sapphire fixes this; in addition to adding more Mega Evolutions, you're able to get over twenty of them during the course of the main game (though you're only able to use Mega Evolution for about half of it).
      • You can ride Pokémon in X and Y, for the first time outside of Surf. The problem? There's only three to ride on. All are limited to one area each, and two of them are slow and cumbersome to control, so it really feels like a throwaway gimmick. The Gen 7 games would properly implement this with the Pokémon Ride system.
    • Gen 7:
      • Pokémon Sun and Moon caused this to Mega Evolution again. While it makes sense since Sun and Moon have a host of other new mechanics to take the center stage (i.e. Z-moves, Ride Pokémon, etc.), Mega Evolution doesn't even play a part in the main story at all, and no new ones were even introduced. It doesn't even get any significant mentions until the post-game and you only get a single one (Alakazamite) for free. To make matters worse, more than half of them weren't even available in the game at all until GameFreak released them through events. The rest must be bought with Battle Points you earn playing in Battle Royales or the Battle Tree. For how much it was promoted both in the games and the anime during Gen 6, the Mega Evolution concept's shift from a hyped new mechanic to being Demoted to Extra for all intents and purposes in the very next installment of the series is somewhat jarring.
      • Sun and Moon brought back Johto's Apricorn Balls much to the surprise of a lot of fans... until you realize that it's only possible to obtain one of each ball. It leaves you wondering why the makers couldn't add some sort of stall or shop in order to purchase more.
      • Some have argued that Sun and Moon's picture-taking mini-game doesn't quite reach the complexity and uniqueness that defined Pokémon Snap.
      • After their popularity during Gen 6, it was a bit of a surprise that Sun and Moon dropped Horde Battles completely; the mechanic would have fit in perfectly, since Pokémon from Alola are said to help each other out a lot. Instead, it got replaced by SOS Battles, which were less useful for EV training and often made catching Pokémon needlessly frustrating.
    • Subverted in Pokémon Ranger: Shadows of Almia. While the "Swimming on a Pokemon" mechanic is indeed used many times in the game, they mostly advertised the part where you do it on an Empoleon's back... something that happens only once in the whole game (Three times if you're going for 100% Completion, two if you already knew about a certain subquest before and take a short deviation when you go there for the first time), while for most of the time you surf on a Floatzel's back.

    RPG — MMO 
  • The Secret World has some players feel this about the investigation quests. The player base tends to remember these quests first when talking about the game, albeit sometimes for the Guide Dang It/Genius Bonus nature of some of them.
  • World of Warcraft managed to avert this after a few years in several ways. Originally, Naxxramas was considered to be a very good dungeon mechanics wise, but the steep barrier to entry meant most of the playerbase would never see it. In addition, several dungeons that are rarely run anymore had unique mechanics that newcomers (or people who missed them in the day) would never see. However, Naxxrammas was moved to the entry level raiding dungeon in Wrath, and several mechanics have actually been incorporated into other bosses since then.

    RPG — Western 
  • Dragon Age:
    • In Dragon Age: Origins, BioWare initially intended for every playable character to become a Grey Warden potentially. Originally, Bioware wanted for the taint to infect all of the companions, meaning the player would have to make them into a Grey Warden. This mechanic was incorporated into Awakening in a way, but there are very few consequences gameplay-wise for not making Nathaniel, Velanna, and Sigrun into Grey Wardens save Nathaniel being executed.
    • Origins also had a unique mechanic during the Fade portion of the Mage quest where the player "shapeshifts" between several different creatures in order to solve the puzzle to escape the Fade realm. However, not only is this mechanic seen at just one point throughout the game, the player never gets to have that good of an experience playing around with the shapeshifting since it's used during said Fade portion, which is considered one of the least liked parts to play through in the game.
    • Post-Origins, the Rogue class' iconic Stealth ability becomes practically useless, since your non-stealthy party members are hard-wired to follow you even if you order them to stay back. Its only use is to quickly de-aggro yourself when surrounded and to shift positions, similar to the Tactical Cloak in Mass Effect. In DAO, by contrast, a good enough rogue could scout out the entire map, stealthily disarming traps right under the enemies' noses and thus making upcoming fights a lot easier.
  • Mass Effect
    • The RPG aspect of the first Mass Effect took a major back seat for Mass Effect 2 where players were vastly limited in the number of weapons, armor, mod upgrades, and character progression, they come across throughout the games. Mass Effect 3 attempted to strike more of a balance between how the previous two games went about its RPG elements, especially with the much appreciated return of mod upgrades, but was still nowhere close to the amount of role-playing mechanics that the first Mass Effect had.
    • In Mass Effect 2, usage of the Hammerhead being limited to DLC, such as the Firewalker Pack and Project: Overlord content, really limited the vehicle gameplay that the first Mass Effect had much more of when it came to driving around in the Mako. It then got even worse with Mass Effect 3 where vehicle gameplay was practically non-existent.
    • Mass Effect 3 had the War Asset Map. The game makes you believe that gathering up armies all across the galaxy was going to lead up to one massive all-out battle on Earth that took into account the choices that were made regarding each bit of asset that was added into the player's army that Shepard brings to Earth. Apart from a few minor cinematic differences, this wasn't the case one bit. None of the war assets gathered up have any effect on the gameplay.

    Rhythm Game 
  • In HarmoKnight, The main character's two sidekicks Lyra and Tyko have their own gameplay styles different from Tempo's (Lyra uses a bow and arrow, while Tyko haves his pet monkey allowing him to attack two enemies at different heights at the same time). Sadly they're used only in very few levels, and only for a third of them.
  • crossbeats REV., unlike the original CROSS×BEATS, lets you raise your scroll speed setting above 5.0, up to 8.0. This is useful on especially slow songs if 5.0 is still too slow for you. Even though C×B continues to be updated today, it still caps your speed setting at 5.0.
  • In spite of being a "DJ simulation" game, only two out of six types of beatmania cabinets offer headphone jacks: beatmania III and beatmania II, both of which are no longer in production. Given that beatmania IIDX is the More Popular Spin-off and the IIDX cabinet is by far the most common of the beatmania cabinets in circulation, this is rather glaring, given that headphones can be very beneficial to Rhythm Game players in arcades that are noisy (which is to say, almost all of them). Even when Konami designed a new IIDX cabinet to coincide with beatmania IIDX 20 tricoro's release, they still neglected to add any headphone jacks!

    Shoot-em-ups 
  • Ikaruga's GameCube port has Conquest Mode, a practice mode that lets you practice parts of stages rather than just whole stages, lets you watch professional replays to understand the best routes for scoring and to figure out useful strategies when playing for the Dot Eater rank, and lets you slow down the game to further refine strategies. Unfortunately, it was not added into the subsequent Xbox 360 or Steam ports.
  • Touhou:
    • Most early games will show a post-game statistics screen, such as the percentage of the game completed, how many lives you lost, how many bombs you fired, how many spellcards you captured, etc. This was sadly abandoned starting from the 10th main game, Mountain of Faith.
    • Spell Practice was introduced in the 8th main game, Imperishable Night, allowing you to practice individual enemy spellcards that you've reached; to compare, Practice Start only lets you start from the beginning of any stage you've reached. For whatever reason, it was scrapped for the 10th, 11th (Subterranean Animism), and 12th (Undefined Fantastic Object) gamesnote , but was mercifully brought back for the 13th game, Ten Desires and beyond.
  • Stellavanity has a variety of useful widgets that can be shown on the sides of the screen such as character starts, a system clock for those prone to Just One More Credit, and points needed until the next extra life. Unfortunately, if the game is set to vertical orientation (for use on a monitor rotated 90 degrees), something a shmup enthusiast is likely to use if they have a monitor they can lay on its side, these widgets are not available.

    Simulation Game 
  • The Ace Combat series is rife with examples of mechanics that are the centerpiece of a single installment and are then completely abandoned by later ones:
    • Ace Combat 3: Electrosphere had complex Story Branching based on the player's gameplay inputs, such as following a certain plane or shooting down a specific target. In the few later games featuring branching plots, such choices are almost always explicit menus.
    • Ace Combat 5: The Unsung War had an intricate wingman interaction system and a Tech Tree that unlocked more advanced versions of the starter planes. While both mechanics were slightly refined in ACZ and ACX, respectively, they have since been completely dropped.
    • Ace Combat Zero: The Belkan War revolved around a Karma Meter named "Ace Style," which dynamically determined the enemies you'd face and their dialogue depending on your conduct at the battlefield. It has never been used again.
    • Ace Combat 6: Fires of Liberation had the Operations System, where almost every mission consisted of several simultaneous sub-operations and you won if the majority of them were completed. No later game reused the same system.

    Shooter — First-Person 
  • Jurassic Park: Trespasser was considered very ambitious at the time it was made, and can still be considered somewhat ambitious today. Mechanics included characters reaching out into the game world, aiming by twisting the player character's hand, and relying on audio cues to tell you of how much ammo you had.
  • Halo:
    • Halo 2 made non-playable allies able to drive vehicles, when previously only human players could take the wheel. The multitude of internet videos of NPCs failing miserably to drive anywhere, not crash, or not kill any of their own allies shows just how useful allowing that was.
    • Halo: Reach introduced the Fireteam mechanic, which causes encountered NPC troopers to join your side as an accompanying squad. However, you have no command over any of these troopers (who aren't exactly intelligent guys) so unless you can give them powerful weapons they'll just be cannon fodder. Additionally, the mechanic isn't available on every level, meaning often times you may encounter troopers but they won't accompany you, rendering them meaningless if you wanted support fire or someone to carry heavy weapons.
  • Gearbox's Opposing Force expansion for the Half-Life franchise offered a few gameplay mechanics not seen in any of the other games such as a grappling-hook with an unattached wall-barnacle and rope climbing.
  • Overwatch had the limited-time Junkenstein's Revenge brawl, in which, in a departure from the usual PvP format, players assemble in teams of four to destroy hordes of robot zombies and four bosses before they all wipe at once or the door they're defending gets destroyed. It ended up being a very popular mode while it was available. Unfortunately, not only was this mode temporary — it only lasted through October 2016 — this PvE format has not been used in a brawl mode of any sort since.

    Shooter — Third-Person 
  • Warframe tends to accumulate these, but one in particular stands out from the War Within quest: Operator mode. Completing the quest allows you to step out of your Warframe as your Operator, but there's barely any point to doing so. You can use it to get past security measures in Spy vaults, clear off damage resistances from Sentients and Shadow Stalker, and destroy Kuva Siphons, and that's about it. It doesn't even tie in with the Focus system, which seems like it should be a logical fit. Somehow, it's even got an underused mechanic of its own. Towards the end of the quest, you get to use Transference to possess the Golden Maw that has been harassing you for a while; all you can really do as the Golden Maw is move around through the bones, and nothing like this ever comes up again.

http://tvtropes.org/pmwiki/pmwiki.php/Main/UnderusedGameMechanic