How to find good free games?

I'll eventually set up my 4k max firestick to be able to run emulators. But meanwhile I'm enjoying some of the existing free games - Crossy Road, Pacman, Asphalt 8 etc. I'm actually surprised at how capable the stick is.

Howerver I couldn't find a way to list only free games (and to not list cloud ones). The search function is horrible, both on the tv and on Amazon's website (I guess they intentionally limit it to encourage more purchases, like the Play Store does).

I couldn't find any adventure or rpg games either

Would also be nice to read reviews, but I couldn't find many online. Any suggestions?