A witty first-person puzzle game that expands on Portal’s mechanics with cooperative play, gels, and larger, story-driven test chambers set in the decaying Aperture Science facility.
- Developer: Valve
- Release year: 2011
- Genre: First-person puzzle-platformer
- Core mechanics: Portal gun physics puzzles, gels (repulsion/propulsion), light bridges, excursion funnels, co-op campaign
- Reception: Universal acclaim for writing, puzzle design, and co-op experience