Stock up on some fantastic indie games, as GOG have launched their Indie Festival which is live now until September 25th, 10 PM UTC. While there's been numerous big releases over the last year, don't forget about all the really great indie games that often do things the bigger lot won't.
Some of the big discounts going include (all of these have Native Linux support):
As Far As The Eye - 75% off
Brigador: Up-Armored Deluxe - 69% off
Death Road to Canada - 74% off
Firewatch - 75% off
Hand of Fate - 80% off
Hand of Fate 2 - 80% off
Into the Breach - 50% off
Serial Cleaner - 80% off
The Coma: Recut Deluxe Edition - 80% off
The Pedestrian - 60% off
Thimbleweed Park - 75% off
VirtuaVerse - 80% off
The full sale can be found here.
If you need help installing GOG games on Linux I can easily recommend the Heroic Games Launcher.