 Some reviewers said that the second act of the game , taking place in the less @-@ structured portion of the old Aperture facilities , may be confusing to some players . Young wrote that in the second act , the game " cranks up the difficulty level at a speed that may dishearten casual gamers " , and said that particularly when traveling between chambers , he had " absolutely no idea where I was supposed to head next " . Kohler wrote that while the player can explore the abandoned areas of Aperture , " none of it ever does anything — it 's just a lot of sterile , duplicated , non @-@ interactive environments " . Watters wrote that the loading time between the game 's levels , in contrast to earlier Valve games , are " long enough to make you take notice and wish they were shorter " . Watters also said that it was unfortunate that the game lacks " stand @-@ alone test chambers and leaderboards ... but even so , Portal 2 is not light on content " without these . Welsh said that the attempt to recapture the spirit of the song " Still Alive " at the end credits of Portal 2 " was a mistake " . Video game critic Ben " Yahtzee " Croshaw named it the best game of 2011 in his review show Zero Punctuation . However he wrote in his Extra Punctuation column that , while Portal 2 was a " very good game " , it unnecessarily retconned portions of the origin game 's story , and did not really further the game 's concept . However , this criticism was directed solely at the campaign , and he stated that he found the game 's co @-@ op to be " much more appealing and much more within the spirit of the original " . 
