It doesn't work because there's no sense of management or responsibility in the project.
So in your opinion what would better facilitate the management and coordination of a project? (I'm not looking to offend anyone here, I'm looking at lessons learned and what can we done to actually make a successful community project).
I'd say the easiest way to look at it is to look at it from a contributer's point of view and see what kind of things would make you less likely to contribute.
For example, if I'm a spriter, I'm probably going to be interested in what sprites are already being worked on, what's left be sprited, what animations need doing, animation quality (ie. number of frames), what's the current quality of the work, overall project schedule or work already done (ie. am I wasting my time as this project will probably fail anyway?)
If I were to think of reasons as to why no one else is contributing code wise in regards to the minish cap engine (apart from I haven't used Game maker for ages), probably the biggest reasons would be:
a) Can't find the latest revision
b) Having a single file makes things confusing, only one person can work on the code at once, otherwise it ends up getting confusing when you have to merge code together
c) It sounds complicated
d) No centralised code direction / information on what needs to be done, eg. if I were to do such and such, how do you want me to go about it