, were you planning to release it as an free mod / open source project?
Couldn’t you have released all the code you wrote and all the freely available dependencies such as OpenRA and Unreal Engine binaries, and have players themselves use the tings you released with their legit copy of Red Alert 2 and other dependencies that are not freely available?
That way you would not be infringing on any EA property or any IP at all.
This is how most engine re-implementations work. Even OpenRA is just code that then downloads freeware assets.