In the original Outcast game, Namjoon, Taehyung and Yoongi were the ones in the house. Yoongi was the first to leave them both, Namjoon was the next, leaving Taehyung as an Outcast. Everyone thought if your health bar gets 0% a character dies but they become the next creator.
After leaving the house, you appearently lose your memories so that is the reason why Yoongi didn't remember anything about the game. Namjoon did because he played it a 2nd time. He knew the house already that's why he was acting on his own at first.
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In the PAST when Taehyung was left alone.
Seokjin & Taehyung talking about the original outcast.