I came up with some game mechanic idea’s as well:
You can do a lot with a mechanic around magnetism. This can go from a puzzle game to walking on walls or the ceiling.
Walking on walls can also be changed to a new mechanic where the whole scene and dimensions change with you when you walk against a wall to make that wall the floor. This can have uses in many types of games like a normal puzzle game, where you have to use the walls and the ceilings to find your way trough the level. A shooter, where you can use the walls to disorient your oponent so you get an advantage over them. Or an agility jumping game.
2. Corruption bar
Another idea can be that you have some kind of bar filling up and when the bar is full, you lose the game. However, when you reach certain points in the bar, you gain extra powers. Those powers can be that you become stronger, jump further, can fly, you become bigger/smaller,…
So, how do they raise their corruption?
Well, there should be two ways. Firstly, simply pressing a button to (temporarily) increase the speed of corruption. Secondly, there should be special abilities that instantly increase corruption.
Maybe a heal action, maybe a speed increase, maybe an explosion, lasers, fire, magic etc.
This all means that the player has to make a careful decision whether to raise their corruption to pass an area, hoping that they will reach the end of the game before their corruption hits 100%, or whether they should leave it and risk dying as a result of being too weak to get through whatever stage.