I respect the fact that you’re owner of this project, however:
It seems not so much of a “development kit” when it is kept closed up from anyone outside of those you know. More like, “early demo of the tech we’re using to make so-and-so”. A “development kit”, in this case, is usually a tool for, well, developing. This tool is up for download for anyone, not just a certain group of people that are working on this one game. Perhaps “engine” would be a better phrase, seeing how most games don’t just release the engine they use.
Oh, wait… we’re using one that was released? Oops…
Anyway, that’s mostly because the engine was basically from scratch.
The main point is that you title the playable demo of the project’s base code a “development kit”. Which I don’t really feel is right, if it will never be released to the public. But that’s what I think. You can do what you want with your project. It just means more work for us who want to make other games. If I make a 3D edit to the Sonic Unreal Worlds project, I’ll make sure to release it to the public if I can.