The boys have differing skills - one is more skilled in sword-fighting (which you are always armed with), the other in magic (available in limited amounts on each level). You collect coins as the game goes on, and spend these in the shop on extra magic, extra lives and enhanced swords.
There are 3 levels to tackle: Earth, The Heavens, and The Sea. These can be completed in any order. The first is straight platform action, the second involves jumping across clouds, and the third sees your characters swim. After those are completed, you must venture into the Monster Castle and finally slay the demon clown Riepotmahn.