And assets, don't forget assets. If you use any bought assets from assets stores (Unity / Unreal, heck even textures from textures.com), the licenses don't allow you to redistribute those in raw form.
Even if you're using only things you have copyright to, it's still not a good idea to license it under same terms as code. Code licenses =/= art licenses
Not sure what your angle is but you can just block a community (or instance). Telling people what they can post usually doesn't work