The Sonic the Hedgehog games have so many Underused Game Mechanics that it wraps back around to being averted, especially with the 2-D games: Every zone will have at least two or three (but usually closer to six or seven) gimmicks, obstacles, and enemies with unusual behavior that's unique to that zone. The large majority of them will never ever return for any subsequent zone or game. This results in the norm being the unique features, and players expect to never see them used again. Here are just a few of the more notable examples.
Main Series Games:
- The Sega Ages re-release of Sonic the Hedgehog has a strangely esoteric Time Attack mode that's only for Green Hill Zone Act 1.
- Sonic the Hedgehog 2:
- Tails' iconic ability to fly is used solely as a means for the CPU to catch up with Sonic onscreen in this game. Many players were dumbfounded by the fact they couldn't use flying when playing as Tails themselves. Curiously of all the official releases of Sonic 2, only the 2013 remaster rectifies this by backporting his Sonic 3 mechanics. Not even the Jam and SEGA AGES versions, which add a ton of other quality of life improvements, bother to fix this (the SEGA AGES version even seems conscious of this and to avoid making Tails a Joke Character, instead disables Sonic's Drop Dash in multiplayer).
- The two player split screen function is a more programming-necessitated example. Only three levels are available in VS race mode, the three that are most compatible in this mode. The beta version had split screen available the entire game, though also demonstrates the mass difficulties the other levels have compressing to two screens, often producing glitchy unplayable messes. The 2013 remaster cuts out split screen altogether in favour of one-screen online play, allowing it to have twice as many levels available in VS mode. When it was ported to Origins however, split screen was reinstated, albeit now fixed to work on the same amount.
- In Sonic the Hedgehog CD, there's basically no reason to go into the futures in the first two acts of the zones, other than out of curiosity. In the Bad Future, it's too late to change anything, whereas in the good future, you've already fixed the timeline, and can get the good future just by completing the act in the past, without any further time travel required. The only thing that matters is going to the past to destroy the Robot Generator. Once that's done, the player just has to head to the goal. If you collect all of the Time Stones by getting 50 rings before the end of a regular act and hitting up the special stage, this gets exacerbated as you've permanently created a Good Future on that save, with no need to even touch the time travel mechanic; later releases tried to at least de-incentivize this by offering an achievement for destroying all the Robot Generators instead.
- Most of the character upgrades in Sonic Adventure are this, but the worst offenders are Sonic's Light Speed Attacknote , Tails' Rhythm Badgenote , and Amy's Spin Hammer attacknote .
- The Rocket Accel in Sonic Heroes is supposed to be a quick way to build speed that allows the team to pass otherwise impassable obstacles such as slopes. However, the speed characters' acceleration is fast enough already that the boost gained from Rocket Accel doesn't make much of a difference, and most levels later in the game are comprised of small platforms above bottomless pits, meaning boosting yourself is the last thing you want to do. Even worse, the only two points where the ability is "required" (the tutorial and conveyor belts in Egg Fleet) can be bypassed by simply running normally, meaning you can easily beat the game without ever using it a single time.
- Using the hourglasses in Sonic Unleashed to switch between the Hedgehog and Werehog. They're heavily used in the level hubs, but the only level the mechanic is used in is Eggmanland, the last level of the game, nullifying any possible exploration of switching gameplay styles mid-level.
- The stages in Sonic Forces where Sonic and the Avatar team up are considered the best-playing in the game, combining Sonic's boost power with the Avatar's gadgets for a lot of variety in level design and playstyle. They're also the least frequent type of level at a final count of four (one of them is almost a Boss-Only Level and another is a brief interlude before the final boss), so you don't get to mess with it much.
- Sonic Frontiers:
- For the first time since Sonic Adventure 2, Sonic can go underwater in 3D. Unfortunately, outside of a few pockets of water in Kronos and Ares, this mechanic isn't taken advantage of with any dedicated underwater platforming segments.
- The Drift is back for the first time since Sonic Generations after being an automated sequence in Sonic Forces, but it's only used in one Cyberspace level, and one of the later ones at that. Depending on the player's choices by the time they finish Chaos Island, they might not even have known it was in the game. The Spin Dash can also double as a drift, albeit one unlockable by end game and as an unintentional bonus of its abilities.
- Pinball returns for only one late game puzzle and never again after that.
- "The Final Horizon" adds new Cyber Space stages, each with their unique gimmicks. The most unique of all is 4-G, which introduces the "Rev Boost", a mechanic where instead of Sonic boosting at the cost of Boost energy, he gains energy while boosting, shifting gears at a certain threshold much like the gears of a car. However, it is only used in this stage.
- While the Chaos Emerald powers in Sonic Superstars are pretty cool on paper and despite being advertised as the game's main gimmick, they're not very frequently well utilized in the game's levels and you can go throughout the entire game without using them once as there isn't really any part of the game's levels that actually require you to use any of the powers. It simply makes the Chaos Emerald powers feel like an afterthought more than anything. With that said, they are generally useful against bosses.
Other Games:
- In Sonic the Hedgehog (8-bit), there is one Speed Shoes monitor in the entire game (in Green Hill Act 1).
- The In-Universe Game Clock in Knuckles Chaotix does have effects on enemies and the level design, but they're all small, subtle things like doors changing position or some of the bosses moving differently.
- Running over water in Sonic Advance 2. Or anything involving water for that matter, since Leaf Forest, the very first level, is the only stage to contain significant bodies of water, and even then they're still relatively rare.
- Late into Sonic and the Black Knight, you can unlock the ability to play as Lancelot, Gawain, and Percival in addition to Sonic himself, and all of them have their own unique movesets and swords. Unfortunately, by the time you unlock them, there are only around four worlds left and you can't use them in any others, denying them any potential usage and replay value they may have had.
