SAN FRANCISCO—The newest tradition at the Game Developers Conference is the “Alt.Ctrl” pavilion. Every year, hackers gather to present some of the weirdest games ever made. Some count as “video games,” while others eschew screens and even computers for content that only barely qualifies as “digital entertainment.”

We managed to play nearly all of the 20 games on show, and this gallery explores some of our favorites. It’s also worth clicking through for more specific explanations of the weird content we got to go hands-, eyes-, and bellies-on with.