If you liked Skyrim try the older Elder Scrolls games Morrowwind and Oblivion. Fallout 3 and New Vegas. The Mass Effect trilogy. Dragon Age Origins and to a lesser extent Dragon Age 2. Crysis trilogy. Metro 2033. Crysis 3 ( and even Crysis 1 still although it's getting old ) and Metro 2033 are very demanding on a gaming PC. Far Cry 1 and 2 are still fun. The Dead Space trilogy.
There's Renegade X which is supposed to come out this year, it's a complete free game started as a UDK mod, it's not Free2Play or any of that abomination stuff. I suppose its more of a tactical shooter, like battlefield, but its more arcady. You know the Command and Conquer stuff.