From a gameplay perspective you could try Devil May Cry 4. However it's more of a hardcore Action/Adventure hack n' slash in that the combat systen is much deeper. The story's not amazing and you'll have to get over the whole Japanese Punk feel of the characters. Other than that, there's Star Wars: The Force Unleashed... it's not quite as polished as Darksiders, but it's got a better balance of story at the expense of less complex combat (in general).
Two Worlds 2? (i say the second one because the first one was a cavalcade of boredom and mediocrity, second one is quite fun though)
Try Chaos Legion Released early 2k, it got mediocre reviews at best but was actually pretty fun for a hack n slash session.
Ah, i remember playing the demo for that. You're right, it was fun but i think the mediocre reviews were justified... didn't really stand out IMO. Now how did i forget about that :|.