There's a site called Chore Wars where everyone in your household can create a character, and their character in game earns experience and goes up level every time the player does some housework in real life. You have to trust the players to self report accurately, but for small households that's not a problem. Not only does it wrap a metagame around the (questionable) game of housework, but it provides a reward and accountability system at the same time. If everyone in the house is level 20-25, except John who is level 5, you know who's been shirking.
I think this idea could be applied to castle design, development, construction, and maintenance. It would require maintaining a database of tasks (quests?), allowing users to create accounts, tracking completion of tasks, assigning XP rewards. Generate a list of obstacles to overcome on the path to awesome communal castledom, and create a reward system for individuals who help the community overcome those obstacles. Designing a room is worth 1000XP, creating architectural drawings is worth double, building a wall is worth a 5000XP, making dinner for the crew is worth 70XP, feeding the fish is worth 20XP, etc.. Every dollar you donate to the general fund is worth 1XP. Community administrators and moderators edit the XP values of all tasks, and tasks that go undone accumulate XP, so that eventually they will be picked up by someone, and the system self-regulates.
Then layer a system of IRL rewards for achieving levels. Castle priveleges are the main reward. Level 50+ contributors can live at the castle for the rest of their lives, level 5 contributors can stay free for a few days, and so on. Even (and especially) the founders are bound by these rules, and the rules are voted on by all contributors with voting rights (level 10+?). The community gets the benefits of crowd collaboration, and evades the tragedy of the commons. There's palpable status, not to mention material rewards for participation. The many kinds of participation all funnel in to a common community reward system that's not primarily monetary, which is key for a system built primarily on love.