Band Saga is a musical roguelike—basically it generates action roguelike dungeons based on its own Genesis-like FM sequencer, which can then be played through. You can generate levels based on importing your own MIDI music, or by composing music within the game (which can be shared with a text string online with other players). Also interesting is that you can change a song while playing through the dungeon based on that song, which would then affect the dungeon you are in. And as you can see from the trailer, the animation is also very nice.
I interviewed Rekcahdam to get a more in-depth look into how it all works, read it under the jump!