Short Story· 1928· Horror
The Call of Cthulhu: 2 recorded works trace back to it.
Works that record this one as a source, with the evidence a contributor gave.
Frictional have been open about the Lovecraft debt across the series, and the design turns one of his ideas into a rule: the protagonist cannot fight, and looking at the thing damages the mind. A sanity meter that drains in darkness and in the presence of the monster is The Call of Cthulhu's central claim made mechanical, that knowledge of what is out there is itself the injury. The fragmented documents the player reads are Lovecraft's found-manuscript structure too.
Gary Gygax lists it in Appendix N of the 1979 Advanced Dungeons & Dragons Dungeon Master's Guide, his published list of the fiction that shaped the game. Lovecraft is on it, and the debt went further than a reading list: Deities & Demigods (1980) printed the Cthulhu Mythos, with Cthulhu among its entries, as one of the game's pantheons.