This rule is really convenient. It lets us focus more on design and saves time on basic stuff we've done a billion times. 

Are there any restrictions on what kinds of assets can be used? I'm not suggesting there should or shouldn't be, I just want to be sure. 

I'm not trying to sneakily submit a whole pre-made game; The jamming process is fun, but the detail of this rule can change a lot of the experience. 

I am under the impressions pre-made art, sound and code functionality is allowed.

Unless made clear, I'm going to be using Kenny's assets for my project, until I am able to produce my own art. Depending on remaining time of course :)