Open Source would be the words you're looking for!
Yeah the whole 'main devs' thing is more like 'top contributors'. Also either Kevin, Glyph, or both technically own the forums to my knowledge. We use github for working on the game and keeping everyone's contributions from getting messy, and the rule of thumb is that you cannot merge your own additions, only other coder's submissions. That way, new content is peer-reviewed in some fashion before being added.
I'd get in on the action too but I am not fluent in programming languages. So I am mostly moral support around here XD