Ok so it is a FPS version of the The Pit. I don't know if you've ever played it (top down, turn-based RPG, very unforgiving) but there is a large multilevel dungeon where the Suulka experiment on all manner of living organisms.

You play as either a human engineer, scout or soldier who descends into the Pit in the hopes of finding the source of a disease ravaging the planet.

It is an RPG at its core but with this incarnation its you get to see the various creatures you encounter up close and personal. It uses the Unreal engine, has a ton of interesting foes, has disease and poison and the ability to find all manner of weapons and gadgets. 

Fully procedurally generated will eventually have multiplayer, crafting and all of the other player characters that are in the orginal Pit roguelike. 

I am currently on my second run as engineer. I died of a disease just as I found the shotgun...*sigh*