It is the NES version. You do have to swap out the chips, but it is still fun. My kids have enjoyed playing it. It's not the original version, but a great alternative if you haven't got the original. Serves my needs when I want to play it. Someone out there burns the roms and then you put them on Golf, baseball, or Tennis. At least that is how mine works. My top screen still shows the old game, but if you select it, you actually play the Galaga. I know you can change the ROM somehow, but I haven't worried about it. It would be fun to learn how to do it.