[mikro]

I am a non-game developer, and I have been looking into this as well for 3D games.

1. It seems the major game engines are Unreal (C++, many AAA titles) and Unity (C#, widely used). Godot is open source and uses a python-esque GDScript. There is also Roblox Studio (Lua) which is its own walled garden.

For multiplayer, you can use Unity and Unreal’s systems or Steam or you could try to roll your own with something like Agones.

For Assets, major tools are Blender and 3DS Max. You could also use tools like Shapr3D or MagicaVoxel. Or buy on sites like Turbosquid but the meshes/textures may not be organized well.

2. Reasoning about geometric transformations can be challenging. Also animations, character rigging, organizing assets, memory management, framerate performance.

All of this is in addition to game design, which is its own thing. Good luck!