I can think of some ideas but most of them are garbage, I would love it if someone could give me their scrapped ideas. My only limit is that I can’t do 3D very well.

Platformer level, with standard stuff, but things get more and more unsettling, until at the end, you find the goal blocked by a monster, that chases you back through the level.

you could do a game where every time you die, you can upgrade a stat 

 you could also do a rogue-like where the map doesn't change so every-time you die you know what ways too go or not to go

If you can't think of anything I have several terrible ideas.

Reverse chess/ other game where you try to lose

Trying to cause Ai to fail a platformer level

Corpses act as platforms when you die

The goal of each level is to die

Jonas has a video on getting ideas quickly in game jams.

A music game where you make a rick roll. you completed the game, but did you win the game?