In terms of SOMA? Nothing's really been made yet.
But Amnesia: The Dark Descent has some pretty notable ones which are story driven rather than scary.
Off the top of my head, you can try:
Amnesia: The Second Dimension which puts you in the shoes of a grunt in a classical 2D sidescrolling game. It can be difficult, but is nonetheless very well done.
Monsters which combines the props and mechanics of Amnesia and Pokemon, a clever and different concept.
Amnesia: A Coward's Debt which looks at exceptional story telling and atmospheric immersion. It's does have its horror themes though, but the story is what really makes it shine.
Alchymist's Rush (2 hours challenge) is an extremely simple mod which will only take you a few minutes to complete, but the actual creation is great. It was created in about 2 hours.