For those wishing to support Valve and their partners for bringing over 500 games to Steam on Linux
along with working on SteamOS and other improvements to the Linux stack like VOGL, better graphics drivers, etc, here's the perfect opportunity to show Valve your appreciation with their annual summer sale.
The Steam Summer Sale is running daily from 19 June to 30 June where there's great deals on tons of titles. Among the titles up at massive (75~80%+) discounts include XCOM: Enemy Unknown, The Witcher 2, and many others.
Check back daily at the Steam Store
through the end of the month for the latest deals.