Cake



The promise of Cake is introduced by GLaDOS as an incentive for Chell to complete the test chambers in the original Portal. It is referenced in many of the Rattmann's dens as a lie, sparking the "The Cake is a lie".

Trivia

 * The cake slice icon shown on the neon panels throughout Test Chambers in Portal appears in another Valve game, Alien Swarm, as the icon of the achievement "Perfect".