While I would like to say Eternal Darkness for the GameCube, that was more so inspired by Lovecraft than based on. So I'd have to go with the Call of Cthulhu for the original Xbox. The game had a lot of weird bugs, but the atmosphere was spot on. It not only left an impression on me as a game, but it was also one of the things that spurred me to start seriously reading Lovecraft's work.
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