As a rule, community projects always fail. For the record, msot private projects fail too, so it makes sense, but more so

More to point, successfgul projects are when a community offers aid, a few people join a team, and the team works on it. (Most 'community' projects are 2-3 core people, a few drifters, and 900 people who talk without commiting. A fact.)
So there are community projects in the team sense..
I think the many-small-teams party game project could work.
But a pure commnity '20 peopel randomly helping out' is tough to pull off; consider ... 20 cooks, one kitchen, one diner.
jeff