Each game mode has its own difficulty. Alpha Gang Stage 1 is normal difficulty. Alpha Gang Stage 2 has no set difficulty I believe. It's just questions you have to answer that are pretty straight forward and easy. Space Pirates Stage 1 is easy mode. Space Pirates Stage 2 is medium. (I don't know if medium and normal are the same difficulty in this game) Space Pirates Stage 3 is hard mode. Goma's stage doesn't really have a set game mode difficulty, but it is harder than the rest. Dinoman is harder than all the other game modes in my opinion because his pattern seems to be more random.
