Acht

The premise of this game is simple: you wake up as a spider, you need to meet eight of your species to turn back to human.
The delivery is poignant. Life, especially as an insect, is cruel and there many ways in which our protagonist can find a premature end.
The only minor drawbacks I found are about navigating the rooms (it can be a bit difficult to render a mental map -- as with every IF, especially Twine).

The horror works well and is apt to your spider form. Recommended game!