GeForce NOW - Installing 'unsupported' games using Steam
This shows how I was able to install a game that wasn't officially supported by GeForce NOW. Stick Fight was the only game I managed to install like this, so your miliage will vary!
It'll be interesting to see how many more games Nvidia add, and whether it gets easier to install games that aren't listed in their launcher app.
Let me know how you get on in the comments!
Check out my other video for a quick lag test of GeForce NOW.