Hey, thank you so much!
For the outlines and cel shader, it's a post process material. On this artstation post, you'll find a paper that explain how to do a similar one.
There are other methods, but what’s nice about this one is that it uses the normal information from your material to generate the outlines. Most of the outlines in the scenes are made with very simple normal maps. for instance, the rock texture is just a basic cloud texture converted into a normal map.
The outlines and shadows are also pure black to give it a dark horror vibe. The game only uses one spotlight and the player can’t move, so I can really focus on making the scene look good from a single angle.
Honestly, my main motivation for this jam was to experiment with a NPR artstyle in Unreal, so I'm still figuring stuff out.