Talk:Custom Game Engine/@comment-70.58.10.88-20130515075548/@comment-29454940-20160805101654

Also, once you've made enough engines you will get events where fans ask to use one of your older engines - typically 4-5 versions back. At that point you can choose to give away the engine or sell it. Giving it away gives you a lot of fans, but cost you very little money, while selling it will make you some money, but may cost you fans. When you have enough fans you gain fans either way. This gives you a one-time income, and won't make you nearly as much as the SDK.

Unfortunately the game lacks the option to license your engines, or buy someone else's engine for that matter.