True about the longevity. That's something I'm planning on focusing on more with X@COM, the next big project (lots of mods and user content). As for Cogmind, I'm somewhat against allowing users to affect the official game content, if only because I'm going for a specific experience that would be difficult for others to expand upon without the same intimate knowledge of the game that I have. We'll have to see, but that's one reason I think a crowdfunding campaign would perhaps have less appeal.
Cogmind is not very open-worldish in design, so doesn't lend itself well to tacking on more content here and there. There is one part of the game where this could be a viable option, and even suitable for a KS reward, but I haven't released any information about it yet, or worked out the details of how I want to implement it, so I'll leave that out of the discussion for now.
There is a good chance I'll be releasing the first version as an alpha with only the core maps available, and add the rest of the optional branches after that. This would be the equivalent of releasing multiple maps over time, though more to *complete* the game rather than supplement it.
If Cogmind is really successful (who knows), I would consider a sequel with many of its own unique maps, since once everything's put together that wouldn't take too long to accomplish by comparison.
The other aspect of the game's design that isn't suited to additional content is that there honestly isn't a huge amount of material to design maps
with. It isn't written like X@COM where you can script in almost any behavior you want. The components of map design are merely layout--tunnels/rooms and doors--and placement of machines, enemies and items. Of course you could mod the machines, enemies and items themselves, but that would be very "unofficial" content and doesn't seem to be what we're discussing here anyway
Cogmind was really meant to be a smaller stepping stone on the way to a bigger game, but it's already taken a year to get this far and there's still probably at least six months remaining. I was thinking in recent days that it's really blown up into a much larger project than was intended, essentially due to feature creep and the thought that "my first commercial game needs to be a good one, let's pull out all the stops." Still, I don't regret the decision to make it much more