For what? For Classic Mac OS gaming you could probably get Sheepshaver or Basilisk II running. Why you would need OS X 32bit apps on a retro gaming system I have no idea.

There are different degrees of retro.

For example you might want to play Halo, Portal. Even though Microsoft bought it before it was released for Mac, there was still a decent size community which extended the original Mac demo: https://www.halomd.net/