If a company wants a passionate programmer, one who has an active Github profile, then in return I want the freedom to maintain that profile and program what I

If a company wants a passionate programmer, one who has an active Github profile, then in return I want the freedom to maintain that profile and program what I want and post it, without the company saying they own every creative thought I have after they hire me. They can have me while I'm working my 9-5, they can have whatever I create in relation to assigned projects. But if I decide to create a cool game engine, or a programming language, or work on a framework, and especially if they aren't paying me for those specific activities, then I should be able to do that on the weekends if I so choose. Without having a constant fear that their lawyers are going to sue me for "giving away company secrets", when that code has absolutely nothing to do with my job at the company.