 Wolpaw said that while many story elements of Portal are revisited in Portal 2 , he avoided some of the memes — such as the frequently repeated " the cake is a lie " . He said , " if you thought you were sick of the memes , I was sick of it way ahead of you " . Wolpaw " couldn 't resist putting in just one " cake joke . The writers did not try to predict or write new memes , and Wolpaw said , " you can 't really plan for [ dialogue to become a meme ] because if you do it probably seems weird and forced " . Portal 2 produced its own memes , including a space @-@ obsessed personality core . Valve later created a Space Core modification for the game The Elder Scrolls V : Skyrim ( see below ) , and the Space Core also appeared as a laser @-@ based engraving on a panel manufactured by NASA for the International Space Station . 
