There are a few I'm currently playing.
Right now I'm playing through the Metro Redux series on Steam, preparing for the 3rd game to arrive in 2018; Metro Exodus.
So far I've finished the first game, Metro 2033, and just started Last Light. Having some issues playing through due to low frames after playing for bit, seems like the only fix is it restart the game.
As for multiplayer games, I've been getting back into Planetside 2 (Briggs server) and kinda just waiting for another game similar to Ghost in the Shell: First Assault to arrive, since it's closing in December.
Got my eye on Black Squad, but there are no AU/OCE servers available, but not too keen on the whole mechanics of the game (personally), feels really clunky.
Other than that, still playing osu!, but more casually as I keep losing motivation to improve or to gain ranks. So I'm just messing around now, switching it up with a bit of Mania here and there.
Some other games I might as well mention just on the side:
Skyrim Special Edition
Left 4 Dead 2
Twin Saga
Final Fantasy VII
The Forest