This looks less like heroes becoming villains and more like villains (who were always villains) tricking the hero and murdering them. Unknown World's founders and developers of the first game all got fired by the company that acquired them.
They didn't sell out. That's a childish view.
They made one and a half games (Subnautica and the dlc turned full release), never made the direct sequel, cut thier losses and cashed thier checks.
If they sold out they'd still be on the dev team, making micro transactions for the corpo.