What happened to Faust in “Guilty Gear Strive”?

In "Guilty Gear Strive," Faust's backstory and fate are revealed through his in-game story mode. Faust is a former doctor who underwent a traumatic event that led him to lose his memories and sanity, resulting in him becoming a deranged serial killer. However, he is eventually captured and sentenced to death, but the government offers him a chance to have his sentence commuted if he agrees to become a test subject for their experiments. As a result of these experiments, Faust's body is mutated, and he gains his iconic paper bag mask and scalpel as weapons.

Throughout the game's story mode, Faust struggles to regain his lost memories and come to terms with his past as a killer. He also discovers that the government's experiments have created other monstrous beings, and he is forced to confront them to protect innocents. In the game's climax, Faust discovers that his former self, Dr. Baldhead, is still alive and leading the government's experiments. Faust confronts Dr. Baldhead and defeats him, but in doing so, he also sacrifices himself to destroy the facility and end the experiments.

Overall, Faust's story in "Guilty Gear Strive" is one of redemption and sacrifice. Despite his past as a killer, he strives to protect innocent lives and make up for his past misdeeds. In the end, he sacrifices himself to put an end to the government's unethical experiments, showing that he has truly redeemed himself and found peace in his final moments.