Tim Cain's main condition for returning to Fallout is that the hypothetical game must be different enough to pique his interest. He emphasizes that his motivation for working on a game is not about money, power, or authority, but rather the game offering him something new and different that he has not done before.
Tim Cain, the co-creator of Fallout, did not want to make Fallout 2 due to a combination of exhaustion, interference, and lack of motivation6. He was burdened with additional responsibilities he did not want, experienced outsourcing of crucial elements without his consent, and faced a significant reduction in his bonus paycheck. These factors led to his decision to leave the project early on in its development.
Tim Cain describes his interest in creating RPGs as being driven by the opportunity to work on something new and different. He emphasizes that his motivation is not about money, power, or authority, but rather the personal satisfaction of exploring unique aspects of a game that he has not experienced before.