Together with Jenova Chen, Santiago co-founded Thatgamecompany. The company's core philosophy centered on creating emotionally resonant and artistically driven game experiences, setting them apart from mainstream game development studios.

Served as producer on "Flow", Thatgamecompany's first commercial release. "Flow" was a notable early success on the PlayStation Network, showcasing the studio's minimalist aesthetic and innovative gameplay mechanics. This project established the foundations for Thatgamecompany's approach to design and production.

Santiago was the producer for "Flower". "Flower" garnered widespread critical acclaim for its artistic direction, emotional impact, and innovative use of motion controls. Its focus on visual beauty and evocative music solidified Thatgamecompany's reputation for creating unique, artistic gaming experiences.

Producer of "Journey". "Journey" is considered a landmark achievement in video game design, lauded for its stunning visuals, powerful soundtrack, and innovative multiplayer experience that fosters connection and cooperation between players. "Journey" won numerous awards and cemented Thatgamecompany's legacy.