I've made a bunch of simple/one sheet rpgs over the past few years. I am gearing up to take my most popular ones and turn them into more fleshed out zines. If you were in my shoes, and you wanted to allow folks to hack/expand on my content, what would you do? Release it under a CC license? Use ORC? Draft a little something yourself? Something else entirely?

To be clear, I don't do this for the money, but my games currently do earn me a few bucks a month. And if that few bucks became a few dozen bucks, well I wouldn't be upset. But this is primarily a hobby for me. I just want folks to potentially buy my game, think 'man this is cool, but what if I did this..." and when they flip to the back/front of the book they see that this is clearly written with the idea that folks will come along and hack it, and that there is a legal mechanism to allow that (along with a few words of encouragement).