 Portal 2 includes bonus content , including four promotional videos , a Lab Rat comic , and an interactive trailer for the 2011 film Super 8 , constructed with the Source game engine . A feature called " Robot Enrichment " allows players to customize the cooperative campaign characters with new gestures and cosmetic items such as hats or flags . These can be earned in @-@ game , traded with other players , or bought through microtransactions at the in @-@ game store . 
