Ah, Dezaemon. This is probably the first game (at least on consoles) to feature a create-your-own engine. This lets you create your own vertically scrolling shooters, a-la Raiden, for example. You can edit enemy flight patterns, levels, graphics, even the music. If creating games isn't your thing, it comes with a sample game (which is DAMN hard I might add.) I love this series :D