I worked for a while on the pirate coop game, and the asymetrical monster city game - and I think both have potential. Lately I've hatched an idea for a strange drafting / sports game that seems to have learned the lessons of previous similar designs. But its proving tough to get past a certain point with these designs.
I think part of the problem is, there is only so much you can do without a playtest group. Furthermore, I think you need hours and hours of playtesting at various levels to make any progress. And while I might have had the possibility of such a group years ago, I didn't take advantage of it, and now the possibility has largely evaporated.
What is the solution? I'm not sure, I suppose I could look for / recruit for a group locally, on craigslist of whatever. Its a bit of an intimidating prospect, but I think a groups of this kind are the only hope for moving beyond the sketches and doodles phase.
But then, is that a goal? The sketches and doodles phase is fun, and maybe that's just where I'll stay. Its a bit useless, but no bigger a waste of time than, say playing video games. And I do feel like I'm honing my sense of what will work and what won't, catching duds earlier in the process, steering designs away from pitfalls I'm learning about.
The latest draft-ball-game is a good example of this - maybe something I'll write up later.