Portal 2, a popular first-person puzzle game developed by Valve, is now available on Steam for Linux, as beta.
The game, released in April 2011, can be played in single-player campaign or in cooperative campaign (multiplayer) and consists of exploring the Aperture Science Laboratory, a complicated, mechanized maze, and interacting with the environment.
The player must solve puzzles by creating portals connecting two surfaces and the characters can use these portals to move between rooms or to "throw" objects or themselves across a distance.
Below you can watch a Portal 2 Trailer video:
(direct video link)
To install Portal 2 in Steam for Linux, firstly buy the game if you haven't already:
Note that the Steam game product page doesn't yet say the game supports Linux, but it does.
Then, right click the game in Steam for Linux, select Properties and on the BETAS tab, under "Select the beta you would like to opt into" select beta:
Valve hasn't published the Linux system requirements for Portal 2 yet but I've tested it using Intel HD 3000 graphics and it worked pretty well (Ubuntu 14.04). However, you can get an idea on the system requirements by taking a look at the Windows and Mac specifications @ Steam Store.
Portal 2 Beta is available for Linux on Steam and costs 14.99€ to 19.99€ (depends on country) / £14.99 / $19.99.
If you encounter bugs, report them @ GitHub.