The game was revealed a few months ago as a retail Wii game, but it has now been switched to WiiWare instead (or "download only" as our Japanese source below reports). There are few details for now, but what we know is that you play as the space invaders (Which are 2D and pixelated, of course) as you swarm cities and other places on Earth to destroy them. There are also various kinds of invaders, which all have different functions. The game's tagline seems to be "Get your revenge" which is certainly fitting.
No price point or release date has been revealed for now. There are a number of screenshots which can be viewed on the game page, however.