Ok I listened to a lot of the replies here. So if I'm going to make this, then I think I'm going to choose Godot as the engine. Why? Because its open source, free, and if something is limiting me or breaks, I can just modify the engine. Another thing is I have read a lot of the engine source code before and its not that hard to figure out what goes on in that engine.
A lot of the games code is going to be first prototype in gdscript, though if there is need for any optimization then c# or GDNative (aka c++), will be used.
Another thing is, modding is the first thing that I'm going to be focused on before anything else. The one thing though I need to decide is what modding language to use which is possibly the most important part. The modding languages I can think about are Lua, Wren(
https://wren.io/), C#, Dart (
https://dart.dev/, if that can be used for scripting, sandboxed, or can even be embedded at all?)