We've mostly just been working with Guidelines here, but we have a Rule now:

Before submitting, write at least one line describing your work and how it relates to the theme in the "Description" section of its page.

If your work's relation to the theme is obvious, I'm sure I'll be able to tell, but I'm going to require that all entries include at least one quick line about the project in general to show that you've read over the jam page and to  discourage spam submissions (or at least make them even more obvious).

Thank you!