If you want to play the game on a PC or a Mac, yes.
You need steam to install Portal 2 Why not? It's free
Urm... you just buy Portal 2 from Steam and then play it...
No portal 2 is the only game that does that.
Portal or Portal 2 mods on Steam is installed by first Downloading it and extracting it. Then copy the map file into your Portal 2 maps folder which is Run the game.
Sure
You don't need to, it will run but with a bit of lag
No. It will cost money. Portal costs money. It was only free for a limited time.
On Steam it will cost $49.99.
Yes. Very yes. Portal was released as part of the Orange Box in 2007 and on steam. Portal 2 was released earlier in 2011.
You can purchace Portal 2 from the Steam Store.Please see the related link to b redirected to the page with information of purchace.
You cannot get a demo for Portal 2, and if there were it would be on Steam as Valve (the creators of Portal 2) distribute all their games there exclusively. However, if you haven't played the first Portal game I would recommend it, and if you like it you'll be sure to love Portal 2!
How many people played portal 2