Working NES squeezed into ... an NES cartridge

All right, we'll admit that headline is a little inaccurate. The heavily modified Super Mario Bros. cart shown above actually plays Japanese Famicom carts (like the not-at-all-bootleg Super Bros. 5), not the slightly larger American NES carts. Semantics aside, we're sure you'll share our sense of awe at the accomplishment of fitting an entire video game system into what, at one point, was used to hold the data for a single game.