Pulcra Vermis

Pulcra Vermis is a first-person puzzle exploration game with elements of psychological horror. In the game, the main character finds himself trapped in a strange dimension with the only thing in sight being a colossal castle. But as if not enough, after lifting a mysterious book from the ground he starts hearing an impassive female voice. 

To progress, you can either follow the voice's plead for help or explore the castle independently in search of three books. There are 3 different endings to the game.