Most of the android TV boxes are pretty low powered. Their primary purpose is to convert a network stream into a video signal for your TV and allow you to pick out a movie from a list. Pretty simple tasks. They still probably have enough power for simple gaming (puzzle games, card games, etc) but not for faster paced RPGs or FPS games. 4K streams and video are a little more intensive so you might expect better performance from a 4k capable box. There are things like the Nvidia shield which can handle those types of games.
TLDR: How well it works, if it works at all, will be highly dependent on your hardware.