Here are some we came up with but chose to not pursue:
- (2D) Items were misplaced in strange places, find and collect them. Heavy focus on narrative
- (2D) Horror exploration game.
- (2D) (Roguelite?) Combat game / Vampire Survivor-like, different biomes(?) and enemies.
- (2D/3D) Wolfenstein-esque dungeon crawler with non-Euclidean mechanics
- (2D) Age of War clone
- 2D Sprites on images of 3D world