Valve's engineers may spend much of their time building practical hardware like gamepads and VR headsets, but they still have room to work on some intriguing side projects. Just ask the company's Ben Krasnow, who recently created prototype game controllers that use the player's butt and tongue for input. The backside-based system centers on a modified bathroom scale that translates posture shifts to software commands; players just have to lean or spin to move their character. The tongue controller, meanwhile, stuffs a mouse's optical system into a custom retainer. As you'll see in the demo videos after the break, neither device is especially practical -- you'd need extra equipment to have any chance of competing with fellow gamers. Still, the experiments show just how daring Krasnow can be when exploring alternative control schemes.