 As of January 2013 , Valve supports fan reuse of Portal 2 content , offering selected assets and assistance . The Windows release of Bastion includes a weapon inspired by Portal 2 's Conversion Gel and turrets ; its developer Supergiant Games received writing assistance from Eric Wolpaw and McLain voiced new lines for the turrets . An add @-@ on scenario for Hidden Path Entertainment 's tower defense game Defense Grid : The Awakening incorporates GLaDOS as an antagonist using new dialogue from McLain and assets from Portal 2 . Wolpaw and McLain also helped to create additional lines for GLaDOS for a custom single @-@ player map commissioned by Gary <unk> , which he used to propose marriage to his fiancee , Stephanie . For a patch for Bethesda 's The Elder Scrolls V : Skyrim that incorporated support for Steam Workshop content , Valve developed a free add @-@ on module that introduced the Space Core as a non @-@ player character that follows the player around . Valve collaborated with Zen Studios to create a Portal 2 @-@ themed pinball table , among other Valve @-@ themed tables , for their games Pinball FX 2 and Zen Pinball . A Portal 2 @-@ themed set is available for Lego Dimensions by Warner Bros. Entertainment and Traveller 's Tales ; the game features additional stories written by Traveller 's Tales with Valve 's blessing set after the events of Portal 2 , with Ellen McLain , Stephen Merchant and J.K. Simmons reprising their respective voice roles , as well as a new GLaDOS credits song written by Jonathan Coulton and performed by McLain . 
