Why does it have to be on the Mac App store? Here's a golf game on Steam that would work on that "tricked out" iMac: http://www.nicklaus.com/news/jack-nicklaus-perfect-golf-computer-game/
After seeing the reviews I think I'll just wait for everybody's golf on the PS4 and buy him one of those.
Honestly thought the mac had come on in the last few years in gaming - if anything it's gone backwards
Thx anyway