Derek Yu

Indie game designer behind Spelunky, Spelunky 2 and UFO 50, founder of Mossmouth

@mossmouth Los Angeles, United States59K followersIndie Game Makers

About Derek Yu

Derek Yu is an American game designer, artist and writer best known for Spelunky, the roguelike platformer that helped define the modern indie roguelite. Born in Pasadena, California, he studied computer science and worked as a freelance illustrator in San Francisco before turning to games full time. Early on he co-designed and illustrated the freeware action game Eternal Daughter, and he became a central figure of the indie scene as the long-time custodian of TIGSource, an influential indie game blog and forum.

In 2007 he and Alec Holowka released Aquaria under their studio Bit Blot; it won the Seumas McNally Grand Prize at the Independent Games Festival and earned enough for both to make games for a living. Yu released the original Spelunky as freeware in 2008, then rebuilt it as a polished remake for Xbox 360 in 2012 and PC in 2013. Spelunky 2 followed in 2020 under his studio Mossmouth.

His most recent project, UFO 50 (2024), is a collection of 50 original retro-styled games framed as the catalogue of a fictional 1980s console company, made over several years with Jon Perry, Eirik Suhrke, Ojiro Fumoto and others. Yu has also written about craft and process, including a Boss Fight Books volume on the making of Spelunky and widely shared essays on finishing games.

Products by Derek Yu

Spelunky

spelunkyworld.com

Roguelike cave-exploring platformer with procedurally generated levels; free original in 2008, HD remake in 2012.

Spelunky 2

mossmouth.com

Sequel to Spelunky set on the Moon, with deeper systems and online multiplayer.

UFO 50

50games.fun

Collection of 50 original single and multiplayer games styled as the library of a fictional 8-bit console maker.

Aquaria

bit-blot.com

Underwater exploration action-adventure co-created with Alec Holowka as Bit Blot.

Eternal Daughter

en.wikipedia.org

Freeware Metroidvania-style action game he co-designed and illustrated.

TIGSource

tigsource.com

Long-running indie game blog and forum community that he founded and maintains.

Derek Yu's journey, 2002–20248 milestones · self-reported

First product
Launch / milestone
Started 2002

2002First product: Launched Eternal Daughter
2002Milestone: Co-designed and illustrated the freeware action game Eternal…
2007Launch: Released Aquaria with Alec Holowka as Bit Blot
2008Launch: Released the original Spelunky as freeware
2012Launch: Launched the Spelunky remake on Xbox 360
2016Launch: Published Spelunky, a book about the game's development…
2020Launch: Released Spelunky 2 under Mossmouth
2024Launch: Released UFO 50, a 50-game collection co-directed with Jon…

Timeline

2002 — Co-designed and illustrated the freeware action game Eternal Daughter.
2007 — Released Aquaria with Alec Holowka as Bit Blot; it won the IGF Seumas McNally Grand Prize.
2008 — Released the original Spelunky as freeware.
2012 — Launched the Spelunky remake on Xbox 360, followed by PC in 2013, where PC Gamer UK named it Game of the Year.
2016 — Published Spelunky, a book about the game's development, through Boss Fight Books.
2020 — Released Spelunky 2 under Mossmouth.
2024 — Released UFO 50, a 50-game collection co-directed with Jon Perry, Eirik Suhrke and Ojiro Fumoto.

How Derek builds

Finishing a game matters more than starting one; protect momentum and cut scope to ship.
Procedural generation and tight rules can create endless emergent stories.
Make small prototypes and freeware first, then polish the ideas that stick.
Building community around indie games helps everyone in the scene.

Learn from Derek Yu

[book]

Spelunky (Boss Fight Books)

Yu's own account of designing and developing Spelunky, mixed with lessons on game design and finishing projects.

by Derek Yu

[template]

Make Games essays

Free collection of essays on game development, including widely shared advice on actually finishing a game.

by Derek Yu

[community]

TIGSource forums

Indie game development forum and devlog community he runs.

by Derek Yu

Derek Yu FAQ

What is Derek Yu known for?

He is the creator of Spelunky and Spelunky 2, co-creator of Aquaria and UFO 50, and the founder of the indie game community TIGSource.

What is UFO 50?

UFO 50 is a 2024 collection of 50 original retro-style games from Mossmouth, made by Derek Yu with Jon Perry, Eirik Suhrke, Ojiro Fumoto and others, released on Steam in 2024 and Switch in 2025.