I've wanted to make a fan game for years, but I could never really justify spending the time. Long story short, I've always enjoyed spriting, composing, and drafting design documents for "hypothetical" projects (50% of the fun with 0% of the commitment!) but in the last few months I've found myself putting so much time into this one project that it has become a distraction from my other creative pursuits. It's in my system waiting to get out, and I've been running from it for over a decade - at this point I either take the plunge and crunch on it, or let it simmer down only to have it resurface again in six months. This happens to be an okay time for me, so I've decided to jump in. ^_^
I've been looking for an engine for the last few days, and while there are workable options, I really like what you're doing (also, I think I'm pretty much right in the middle of your target audience.) I know this is a long-burn project for you, and I understand your time-frame for adding the required features to support a fully releasable game might not work with someone looking to go into production this very instant, but I think we might be a decent fit. I've got a fairly detailed plan, a bunch of assets and ideas to test, and while I don't have any coding experience I am a bug-hunting machine (I've done several years software QA, both with publishers and in-studio.) Also, I'm patient and already expecting this to take a long time to get right.
Let me know if you're still looking for a fan game on which to collaborate (I plan on doing most of the rest of the work on my own, but I consider providing the engine at worst a 50/50 effort.)