Cthulhu is a single-player modification for Half-Life. It contains 65 maps, 21 new monsters and 14 new weapons. Aeons ago, Earth was ruled by The Great Old Ones, beings so alien and terrible that merely seeing them would drive most people mad. Before man's ancestors climbed down from the trees, these being were defeated in a war with The Elder Gods. But their alien nature meant that they could not be slain in any way that we would understand, so they were imprisoned. And so they wait, patient and potent until the stars are right and they shall walk forth once again and wipe mankind from the face of the Earth. You play Ranulf Stafford, an occult investigator in Arkham in the year 1928. Drawn into a nightmare chain of events, you find yourself the only thing standing between mankind and the return of Cthulhu, one of the most dreadful of The Great Old Ones.
There are some really innovative ideas here. Sadly the execution is not so great. There were some really cool enemies and weapons, and the environments were varied. However, Some models could have been better and the mapping was bland, uninspired, and confusing. Default Half-Life textures where mixed with higher resolution custom ones which is a pretty big mistake. In addition to this, the sanity system is terrible. Since it barely ever regenerated, the player was almost never able to use magic, which was a really cool part of the mod. I needed to cheat in order to defeat the monster at the docks because I had used all my sanity prior. Nevertheless, this was a fun, albeit occasionally frustrating mod that I would recommend, as long as you have the walkthrough handy.