Valve has released the official cover of Portal 2, sequel to the controversial puzzle game which also saw the addition of online co-op and will hit stores on April 22, 2011. He was finally updated the site for the occasion of the Opening Science has two movies you happy holidays: the first one to see some nice blocks in front of a cake and a Christmas tree with the modified version of the song of Portal, Still Alive, and the second with the only variant of the presence of orange bot download at ' address .