Hey saw this yesterday and got it. Looks like it expires today. Had to link my Steam to Humble.com but they are legit. Go a free game. See these deals before but usually it's something I have or don't care about.
Just thought I would share. I played it last night runs on highest settings on my RX 580 @ 1440p, and looks great and ran without issue.
Only good for the next 22 hours. Sorry should have posted this yesterday to give you all more time.