A horror game about navigating tall grass (either from within or above) with who-knows-what lurking around ready to attack you. A predator animal, a monster, a swarm of insects, whatever.
Also, you find hints along the way of what it is, where it’s been, etcetera.
Instead of animals, it could just be scary stone totems or statues (or whatever 3D assets I can get for free/make myself). Need no animations. Easier to produce.
Vaguely inspired by this (which is otherwise completely unrelated): https://www.reddit.com/r/godot/comments/1u4sgq5/grass_cutting_mechanic_ive_been_working_on/