sounds like an awesome idea. We could participate with the one game a month site, or do our own version, or both
it's be nice for the community here to pick a theme each month and everyone work on it and share results.
i'd suggest that rather than the theme being something specific like portculis (it kind of ties your ideas to a castle setting) it should be something more abstract to encourage innovation and variety.
i'd suggest a theme like parenthood, or the unknown, i dunno, just not something that's gonna produce a bunch of different castle games.