Diablo (studio: Blizzard). I started with Diablo 2 and fell in love with the eerie, dark fantasy feel of the game. Each main level was a different city and had its unique theme. I got into the lore once I read my first Diablo book: Legacy of Blood (Richard Knaack). He managed to capture the dark essence of the Diablo world in vivid detail. After this book, I dove headfirst into all the remaining works, including other authors. The Diablo trilogy is really good if you want to learn about the overall lore and main conflicts. It's basically about heaven and hell warring over control of the mortals, and ironically in the process they are invading and destroying the mortal realm. In Diablo, the heavens are just as bad as the hells. The nephalim (mortals) must fight both to save themselves. If you like dark fantasy, Diablo lore is definitely worth checking out. And I am still waiting for a game that can so accurately and vividly portray a dark eerie setting like Diablo 2 did so well.
That's where my name came from. Deckard Cain is awesome. Shame that there will never be a sequel to Diablo II to continue his story. Damn shame.