The issue with many emulators is that they need a LOT of RAM. ATI Graphics eMacs are limited to a max of 1G RAM, plus have fairly limited vidoe hardwre taht likely would not meet teh sysreqs for VRAM on any modern game.
OK, I just checked the sysreqs and it want a 1.6ghz proessor (the fastest ATI eMac was 1ghz), plus found this:
Video Card: 128mb Video Memory, capable of Shader Model 1.1
The most VRAM any eMac ever had was 64MB.
The game is fairly recent. I suspect no PPC mac could deal with it regardless of method.