I've been playing Thief Gold. Great game that really surprised me in how well it holds up. It somewhat runs out of steam in the last third though, where I currently am. Missions like "Escape" have been a bit of a pain with their difficulty and aren't as well designed. Still intending to finish it and get to Thief 2, supposedly the best in the series.
On Steam, I've been playing "Songs of Syx". An amazing mixture of Dwarf Fortress, a city builder and even a bit of a civilization-building RTS. Really addictive game that's complex but not overwhelming.