So far, for me, it has been:
º Diablo III: Reaper of Souls (got some good characters, mostly Barb, doing a few Rifts daily, like two or three of them every day)
º TERA Rising (MMORPG, just casually doing some random PvE stuff, nothing serious, burning time)
º Mass Effect 3 Multiplayer (love it, 1,100+ hours in it so far)
º Borderlands 2 (+DLCs, still finishing a few DLC-related areas, need to finish Badass Crater of Badassitude)
º Shadow of Mordor (pretty fun game! will complete it in the coming day or two)
º WH40K: Dawn of War - Soulstorm (modded offline skirmishes, mostly)
º Skyrim (the glorious Skyrim, that game could probably keep me sane my entire life if I let it)
And that's about it so far, there's a few minor ones here and there (Plant Vs Zombies, Super Meat Boy, Terreria, etc) but the main ones are listed above. I might give a go to Alien: Isolation but I'm waiting for a price drop, probably this holiday sales on Steam (but that's going to be after Inquisition).