The "Perpetual Testing Initiative" has been expanded to allow you to design co-op puzzles for you and your friends!
Developer: Valve, Publisher: Valve, Game website
Windows | Mac | Linux | Steam Achievements | Full controller support | Steam Trading Cards | Steam Workshop | Steam Workshop
- OS: Windows 7 / Vista / XP
- Processor: 3.0 GHz P4, Dual Core 2.0 (or higher) or AMD64X2 (or higher)
- Memory: 2 GB RAM
- Graphics: Video card must be 128 MB or more and with support for Pixel Shader 2.0b (ATI Radeon X800 or higher / NVIDIA GeForce 7600 or higher / Intel HD Graphics 2000 or higher).
- DirectX: Version 9.0c
- Storage: 8 GB available space
- Sound Card: DirectX 9.0c compatible