スタンドアローンのPortal Modが複数存在

・Portal

Rexaura
https://store.steampowered.com/app/317790/Rexaura/?l=japanese

Portal : Prelude RTX
https://store.steampowered.com/app/2410180/Portal_Prelude_RTX/



・Portal 2

Portal Stories : Mel
https://store.steampowered.com/app/317400/Portal_Stories_Mel/?l=japanese

Portal Reloaded
https://store.steampowered.com/app/1255980/Portal_Reloaded/?l=japanese

Portal : Revolution
https://store.steampowered.com/app/601360/Portal_Revolution/?l=japanese