The big reason, in my opinion, for there being few successful FOSS games is that the only thing bringing the team together is a shared vision. This makes it muc

The big reason, in my opinion, for there being few successful FOSS games is that the only thing bringing the team together is a shared vision. This makes it much harder to succeed at a large project unless the project is inspired by/a clone of a nostalgic game, or is in one of the dream-niches that are now being colonized by Kickstarter projects. It's the same reason there are a lot of failed mods: putting a team together is hard, and content production isn't exponentially scalable like code is. Which is not to say that there aren't lots of open source games: every Ludum Dare Compo game is required to be open source, which is tens of thousands of games right there. There are a few "big hits" in the FOSS world: Battle for Wesnoth, Vega Strike, FreeCiv, 0 AD, Nethack, Angband, etc. The ones that don't start of clones of commercial games tend to be at the end of a long heritage of open source development: roguelikes, Netrek, and the like. _Playable_ projects with ongoing development often accrue a very dedicated fandom. It's just hard to get to "playable enough". The real breakout for FOSS and games has been in development tools: open-source engines and libraries have been one of the major reasons that this as become a golden era of indie game development. Even commercial tools like Unity rely on the existence of Mono, for example.