Humble Bundle has a new set of games ready with the Humble 2K's Game Together Bundle, there's a few nice picks for Linux gaming fans in it and more if you use Steam Play Proton.
For actual Linux support, there's not a lot. What's there though, is definitely good. In the first tier for £1 / $1 you can get Spec Ops: The Line for Linux. Plus there's also The Darkness II, Sid Meier's Pirates! and Carnival Games VR.
If you pay more than the average it includes the BioShock: The Collection, with that having BioShock Infinite as part of the package which does support Linux and is a huge amount of fun. There's also The Golf Club 2019, Sid Meier's Civilization III: Complete and NBA 2K Playgrounds 2.
The top tier includes XCOM: Enemy Unknown Complete Edition (one of my favourite strategy games), Borderlands: The Handsome Collection (Borderlands 2 + The Pre-Sequel and a bunch of DLC) all of which support Linux there. Outside of that there's also Borderlands Game of the Year Enhanced, WWE 2K20 and NBA 2K20.
With the selected charity, International Medical Corps, getting a portion of the proceeds too.
See the full bundle here if any of that interests you.