iso is different from .zip. .zip compresses files into a compressed folder format. iso is an image of something like software generally,( like windows, games etc) either one will do, to run an .iso, you have to burn to dvd or CD and run from there. .zip just has to be "unzipped" and decompressed to access file contents.
zip is an archive, iso is a disk image. Both are just a packaging for the game though, so we can't tell you if your game is going to work. It needs to be either Universal or PPC-only. If its exe - its a windows game.