Super Meat Boy - If you havent played it yet, amazing price.
Titan Quest - Must play for ARPG lovers imho.
Edit : By the way this is by far one of the best threads i have seen in a long time, thank you everyone for contributing amazing hidden gems! I already purchased five i saw here.
Titan Quest
Price: $14.99
Platform: Windows
Steam Description: The Titans have escaped their eternal prison, wreaking havoc upon the earth. The gods seek a hero who can turn the tide in an epic struggle that will determine the fate of both men and gods. Are you ready for the quest? Features include awesome RPG action, vast worlds, co-op gameplay, and a world editor. This game was recently featured in the Humble Bundle.
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Its definitely multiplayer. You made me recheck the steam page.
Immortal Throne is a great addition as well though, one of the classes was a bit OP I believe.
In between D2 and D3, I played the only game I have ever seen that is even close to Diablo, and that is Titan Quest. You may not agree, but I think this game is as close as it gets to the real thing.
> for an early access game it's surprisingly complete.
Seeing as it's been in development for ~6 years I'd hope so. It's made by a lot of the same people who made Titan Quest, same base engine too.
Trine apparently can support multiple multiple keyboards/mice/controllers, but I've never tried multiplayer (note it is "couch co-op" only).
Titan Quest if you like diablo style dungeon crawlers.
Good place to check for other possibilities is Co-Optimus