Selling source code tips?

Does anyone have any experience, recommendations or advice on selling source code?

I have been working on a project for a few years and I am thinking that it might make a good starter kit with a little work. It is a CCG/ card battle game like Hearthstone (in fact, over time I just started implementing the same cards to test functionality. If you are familiar with the game you’ll see some familiar cards/spells). It started as a cocos2d project and I have re-wrote it many times for optimizations or excuses to learn something new. For instance, I rewrote it the first time when cocos2d 3 was released and I was learning the new renderer. My latest rewrites were for 3.5 and to learn swift/spritekit. I am also looking into porting it to Unity.

Anyway, just looking to see if anyone has had any success selling source code or has a recommendation on where to do so. Posting a highlight video and there are some full battles with the AI on the youtube page as well. Thanks!