just copy + paste this into your steam browser:
steam://run/534615/

alternatively go to steam developer days on:
http://psteamproxy.yuanyoumao.com/app/534600
and check out the video "6. Getting Started with Linux Game Development" in the 2014 tab

its already 4 years old but back then gnu already rocked for gaming, nowerdays its even more developed into that direction.