Quantum Conundrum is a puzzle-platformer video game developed by Airtight Games and published by Square Enix. It was directed by Kim Swift, who formerly worked at Valve as a lead designer on the critically acclaimed Portal.

Conundrum is a puzzle-platformer viewed from the first-person perspective. As the boy protagonist, the player can run and jump, interact with various switches, and lift light objects. The player can die by falling into toxic liquids, bottomless pits, or falling from too great a height, and if hit by destructive lasers; this will restart the player at the start of a puzzle or a checkpoint if passed. The goal of each room is to reach its exit door, though it may be necessary to activate certain switches or other devices before the exit can become available.

Most puzzles require the player to manipulate the room and objects within it using four different dimensions which impart unique physical properties to the world. The four dimensions are the Fluffy dimension, where objects are ten times lighter than normal, allowing the character to pick up most non-fixed objects, the Heavy dimension, where objects are ten times heavier than normal; the player cannot pick up any objects, but their new density allows them to avoid destruction by laser beams, the Slow dimension, where time crawls to ten times slower than normal, though the player moves at normal speed, and the Reverse Gravity dimension, where gravity is reversed, though the player is unaffected by this.