Made with GameMaker, What's in the Box sees you controlling an infinitely expanding robotic arm tasked with carrying a box across the game's levels. These include barriers that will block either your hand or your box.. Other hazards include roaming enemies, spikes, portals and conveyor belts. Only by beating the game with a low number of failures will you discover what lies inside the titular box. Otherwise, its content gets corrupted.
What's in the Box is designed to look like a BBC Micro game.