We strongly recommend that you buy the game so you can support the developershttps://store.steampowered.com/app/620/Portal_2/
WHAT IS PORTAL 2
The "Perpetual Testing Initiative" has been expanded to allow you to design co-op puzzles for you and your friends!
HOW DO I INSTALL PORTAL 2 ?
1. Click the green UploadHub button and you should be redirected to the Download.
2. Once PORTAL 2 is finished downloading, extract the .rar file. (You will need WinRar, you can get it here
3. Once its extracted, go into the games folder and right click the game and run it as administrator and Enjoy!