Stardew Valley has sold nearly 50 million copies, outselling major video game franchises like Pokémon and The Legend of Zelda, and has fostered an online community with a reputation for being kind.

After 15 years working on Far Cry, Splinter Cell and Rainbow Six, veteran developer Patrik Méthé is doing something different — a blockbuster open-world action RPG starring a hulking bird warrior.

Eighteen months after the Turning Point USA founder helped the company launch its blockbuster series, Surrounded—and six ...