Wii Fit software. But unless we're being badly deceived, the knockoff balance board should operate just fine with the official game (seriously!) -- assuming that you can find it by its lonesome, which you can't. The best (er, "only good") part? It's actually in stock for $92.95, which is more than the Big N can say about its genuine counterpart in much of the world. It's okay, we know you're seriously considering this over that eBay auction -- we promise not to tell.