A 2007 first-person puzzle-platformer that uses a handheld portal device to solve physics-based challenges, blending dark humor with elegant, minimalist design.
- Developer: Valve
- Genre: Puzzle-platformer, first-person
- Platforms: PC/Xbox 360/PS3 (via The Orange Box); later standalone on multiple platforms
- Mechanics: Portal gun creating linked surfaces, momentum conservation (flinging), weighted cubes, timed switches
- Notable: Memorable AI antagonist GLaDOS, dry humor and narrative reveal, iconic end credits song "Still Alive"