Many people develop their game further after Ludum Dare.

I, for my Ludum Dare entry, had to make a simple physics engine, because nothing else would work for me. Well, I liked that physics engine a lot, so I developed it further, before even considering working on on my game. I improved the support for semikinematic rigid bodies and their interactions with other semikinematic rigid bodies, extended the engine to 3d and did some other improvements as well. Just now I published the 0.1.0 version of this physics engine under crates.io. It's free to use for personal and commercial projects and is an easy way to include simple physics in your Bevy game, for example for jamming or prototyping. Happy developing!

Do check it out and also do check out Bevy, because it's a great way to get started with simple and even the more complex projects.