Yes it is but there is co-op where you can be P-body or atlass
its from the game portal and portal 2
Portal 2
Chell is the main player character in the Portal video game series. Chell appears in Portal and Portal 2. Chell was modeled on Alesia Glidewell and was voiced by Mary Kae Irvin.
Will that heartbroken
...ummm...Portal?
Ok Portal still alive is bonus levels and there is a game called portal 2 already
Portal 2 is a co-op game rated E10+
Half the game is single-player and the other half is co-op (2 players). They each take around 3-4 hours to complete.
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.
It depends on your own experience of Portal 2. Did you enjoy the game? If you did then it is of course, worth playing the very first Portal Installment.
The only in game editors for portal are these 2 which I can think of: 1.garrys mod (not really much of a game EDITOR) 2.Valve's hammer editor, where you can create your own levels for more or less every game on steam (although im not sure and its very complicated)
the Orange Box gives you 5 games in one, Half-Life 2 and episodes 1 and 2, Team fortress 2, and finally Portal. all complete and all very fun to play. Portal is a game that is found in the Orange Box