Alternate Bitcoin networks

I'm learning about Bitcoin and how it all works, and was wondering if there are any alternate Bitcoin networks and communities that people use to essentially play around on?

I.e. networks like the early days of Bitcoin where it's easy to hash blocks on a laptop and a coin has no value so you can trade coins etc for free?

Being a small network transactions would be quicker and easier to trace, and follow around.

I've tried Google for some, but just get drowned out by all the altcoins people are trying to get rich from.