HITMAN from IO Interactive and the Linux port from Feral Interactive is a great game worth your time and monies, plus you can try the whole game across this weekend for free.
While the game has the first opening section free anyway, this Steam Free Weekend allows you to progress through the entire game. The amount of freedom you get in HITMAN is brilliant, I've ended up spending multiple hours in a single mission in one sitting before, trying to mess with all the targets as much as possible. If you love experimenting and watching things unfold, it's a really fun game.
Oddly, IO didn't seem to announce it anywhere despite it going live yesterday. It's happening as part of the HITMAN Franchise Sale on Steam. Update: IO did tweet about it today a few hours after this article went live.
Find HITMAN on Steam.