Nothing. The answer is, literally, nothing. These transforming LEGO Game Boys combine the best aspects of the childhood of every kid who had an awesome childhood.
Domaster and Tetrawing—as the duo above are called—have come directly from outer space, where they were created by intergalactic LEGO master Julius von Brunk. Sure, they don't actually do anything, especially if you consider the batteries turning into laser guns nothing.
Alright, so we probably love these a little too much. Is our enthusiasm warranted, or can you come up with an even better nostalgia bomb? Let us know in the comments or on Twitter.