It looks like you're new here. If so, welcome!
A *.love file is just a *.zip file in disguise, so if you rename it to "whatever.zip" and extract the contents, the original files should be right in there.
Most of the code is in "main.lua".
Better still, if you install love (from the main page, http://love2d.org/) then you can run it.
I'm only assuming you haven't got it because I can't see why else you can't run it
This is pretty old now, and I have a feeling the code's messy, and I've been meaning to finish it, but I haven't got round to it yet...
Anyway, there are loads of love files on these forums, and they all contain source code. Neat.