Looks like another good Humble Monthly has just arrived, as the early unlock game is the strategy title BATTLETECH which has Linux support.
Checking SteamDB, looks like this is the cheapest BATTLETECH has been so far too. In this case, it's even better value since you get a bunch of additional games unlocked next month. On top of that there's access to the Humble Trove, their curated selection of DRM free games and there's plenty in there that support Linux too.
The unlocks for the previous Humble Monthly were pretty good too. Slay the Spire, Distance, State of Mind, Guacamelee! 2, Squad, MOTHERGUNSHIP and God's Trigger. Plus the Humble Original game Shady Knight. Works out quite nicely since I wanted to try out MOTHERGUNSHIP with Steam Play for a while.
A good deal, check out the Humble Monthly.