I've recently discovered two games that have monopolized all of my gaming time:
Divinity: Original Sin and State of Decay. The former is a fantastic RPG set in a fantasy world, involving a very dynamic (and co-op capable) character relationship system & extremely open-ended approaches to problem solving; the latter is possibly one of the best zombie apocalypse games I've ever played. It's also RPG-ish, in that you play multiple characters and level them up, but gameplay feels more like GTA. The need to scavenge for supplies, keep your group's morale in check, focus on multiple characters, etc... it's as close to playing "The Walking Dead" in an open-ended fashion (unlike, say, the Telltale version where it's a scripted story being told - also brilliant, but different) as I've ever seen.
I highly recommend both.
Other than those, Far Cry 3 and XCom: Enemy Unknown are frequently visited, and Skyrim gets a go now and again. The Stanley Parable is worth getting on sale just to experience.