@sinbad @lisyarus It's not so bad! I made a couple of small co-op games in Unity and I was working on another in Godot earlier this year. They were a mix of client and server authority.
I think the first one kind of sucks as you learn the patterns and ways of thinking, but then it becomes easier. Also, if your networking library isn't polished and proven it'll be a headache. Netcode for GameObjects in Unity was occasionally a real PITA when I used it last year.