VisualBoy Advance is by the far the best and most popular GBA emulator. And in fact it does much more than only GB Advance emulation. With it you can play GB and GBC roms as well as games made for GB Pocket, Super GB and all the games compatible with GBASP. So if you are looking for a single emulator that would play all GAMEBOY games this is the one you need. To define emulator keys go to Options -> Joypad -> Configure -> 1. When you have finished downloading the emulator, then unzip it to any folder on your PC/Mac. Run the Emulator by double clicking on the VisualBoy Advance.exe. You can play the rom by dragging and dropping the rom file on to the VBA window or click on File > Open > Select ROM > and then you can browse your disc and select GBA rom to emulate. One of the features we like the most about this emulator is that it supports GBA roms that are inside zip files without a need to unzip them. So you can have your entire GBA games collection zipped and save a lot of space on disc.