This is Half-Life: Lights Out. It is a self-explanatory mod that involves the adventures of Gordon Freeman, but only if his adventure was darker. No, not gritty darker, like, you can't see darker. If you can beat this, let me know. Because, without TAS, it's impossible.
The crappy mod itself. Put directly into the Half-Life install folder.
By crappy mod you mean broken? You not only managed to **** up by not making every map pitch black, but you also ****** up multiple level changes, the one in which you're about to encounter the first free headcrab loads you outside of the map, couldn't tell if it even was the right map, couldn't noclip, even though I had sv_cheats on beforehand, and there are level changes that are just missing completely, leading to nothing but a giant wall, I finally made it to a map that was pitch black again, and didn't spawn, do you even know how to use Hammer? You even had the skybox set to the wrong texture in the Xen intro during the anti-mass spectrometer section, and I'm pretty sure there's a pure black skybox texture in base HL1 (I seriously hope this isn't an issue on my side, I doubt it but it worries me that no one else has complained)