I found the issue, but it will take a while to fix.
I develop on linux and cross-compile to windows so don't always catch these bugs. Now I switched to windows and it will be fixed when I have everything running on the new environment.
You probably don't have Java installed. You can download and install Java. Or if you dont want that you can wait 2-3 months when I have the new version. It will run out of the box without hassle.
Thanks for your feedback! I made a simulation similar to this one where you can make your own reactions. Click on universe assembler and type something like
p0 p1 -> p4 p5;
That will turn type 0 and 1 into 4 and 5. So you can set all the reactions yourself.
Thanks for trying it out! In chemistry life every combination of particles had a different radius where they interacted, thats why you don't see those shells anymore. I'll add it as an option in the next version.
The .zip file has the Java Runtime Environment bundled with it, its for people who don't have Java installed. If you have Java you can also run the .jar file.