Both the Jam and the Compo allow you to use existing base code so you don't need to wait to start coding your game. You can use placeholder art/music/sounds/etc. to test. Even if you end up wanting to switch genres for the specific theme, you'll be able to reuse a lot of your base code.

Check out all the rules here: https://ldjam.com/events/ludum-dare/rules

And the FAQ, which covers A.I. use too: https://ludumdare.com/resources/questions/