Pros:
+The way all the different power ups have their own unique abilities is really neat. They're not just extra hit points or extra powers (mostly), they really add unique ways to get through a level.
+There's a lot of great designs, from the various power ups to the enemies. The stages look quite nice too.

Cons:
-Controls are slippery as hell and make any kind of platforming on small blocks impossible.
-It's got that unfair old-school difficulty, with many terrible game design choices.
-The level layouts are pure ass. Each stage is like a huge labyrinth with multiple dead ends. A game with multiple paths is great, especially when you can tailor each one to the specific power ups. What isn't great is making like 50 paths in a level and having 49 of them just lead to nothing.
-Enemy placements/bottomless pits and the like are placed in often unfair positions, making a lot of blind drops or sliding down a hill straight into a row of spikes.
-Many times the game requires you to progress via a random hole in the wall that is indistinguishable from a normal wall.
-The game is very unintuitive. I got a power up that sent huge lasers from my mask, so I figured it'd be a damaging thing. Turns out they reveal hidden blocks. That costume with the giant knights helmet? It lets you climb walls for some reason.

Mixed/Not important enough to be a pro or con:
~This goes in with the unintuitive, the first obvious assumption for the collectable gems is that they grant an extra life at 100 like all platformer collectables that are everywhere. Then I got 99 and the rest just kind of disappeared...weird. Turns out the gems grant you a bonus power that changes depending on your costume. That's such a neat idea, but why to activate it do you need to press a button combination that makes no sense? It isn't even mentioned on the controls screen in the options.

Note:
•So I was planning on completing this, but my save state got ruined. Probably fair to call it abandoned though since there's no real in-game save so you're supposed to complete it all in one sitting, despite the fact it has over 100 levels of pure BS.

An SRAM patch came out so I finally had the chance to play this on a CRT with the benefit of savestates

And goddamn you can tell they didn't actually anticipate that people would try beating this. It feels like once they had the idea for a 100-level game, they went 'no kid is gonna get even close to the end, let's just make everything past stage 7 as evil as possible'. This isn't the hardest platformer of 4th gen but it does everything in its power to misdirect and frustrate you, and with just 3 lives and continues, I don't actually understand how anyone could've finished this before the internet. But despite that, KC's difficulty is like, really well done? Like, none of the challenges here feel like the usual lazy tropes that other mario/sonic ripoffs were using, everything feels intentional and fairly well-designed. It's still fun in a masochistic way, almost like a 'lite' interpretation of what kaizo mario would eventually become.

also this game just has the best vibes. i miss when games would just make their game some bratty-ass teenager who thinks he's hot shit. if someone made this today it would be fucking drenched in irony and self-deprecation.

(sonic's ultimate genesis collection 12/40)

i FUCKING HATE THIS TGAME'S LEVEL DESIGN IT'S SO UNFAIR. but also??? everything else about it i began to develop quite the soft spot for. i love all the characters you can turn into and especially their designs, its quite a solid looking game, and the soundtrack is memorable. i usually would not look past level design so, Miserable, but like, a game has to be pretty fuckinh cool to make an exception to that yknow?

(later addendum: nah im lowering but only a little)