My last ludum dare failed, because I realised halfway through that my plans were too big. I had planned three minigames that worked together, but I would never have enough time. It is better to get something out there, rather than go too large, and then give up halfway through. I do not want to discourage, but especially if you're working alone, try and keep it to something you know you can finish.

There is going to be plenty of work to get through, even for the smallest idea. Good luck!