Metroid Prime: Blast Ball was a surprise free release on the 3DS eShop, offering the multiplayer portion of the game before the release of the full title. With single, local, and online play, the demo was pretty robust in showing what Blast Ball was all about.

It looks as this was primarily a server test, as it was recently discovered that Nintendo will be shutting down the demo portion of the servers in early September due to the release of the full game. You will still be able to play single player and local multiplayer with the demo though, so if you have some friends and don’t plan on picking up Federation Force, you can still have some fun.