Neat idea, at least until google adds the same thing into Google Play Games, and gobbles up the market from underneath you.

What games does it support?

Can I use this for other play store games or is it just for your ecosystem of games?

But not available for the nexus?

Not compatible with Nexus 6 for whatever reason. Needless to say, I'll pass.

This is what google's remote app should have been.