If you thought HL Xen was bad, this is sooo much worse. You just run around through caves. It's just dark and wet. Basically a spelunking simulator. Barely any enemies to kill. But... you start finding more weird... ancient alien ruins?
@BigTony
It's a mod. That's what the maker included in it.
@BigTony
Residual Life. It's pretty good overall.
And then it gets full blown weird... I didn't know what to think of it at first, but after a while it reminded me of the Combines.