This is a great site which has a bunch of great tutorials on mesh construction, rendering, hex maps, procedural noise and a couple of full games all made with Unity.
Great range of videos covering role playing games, character controls, space shooters, first person shooters, virtual reality amongst a huge range of other stuff.
Similar to BurgZero Arcade, this is just a great resource for learning all kinds of stuff like hex based games, path-finding, physics, multiplayer, destructible objects, etc.
While not updated anymore (>2 years since the last video) UnityChat has some good videos surrounding real time strategy games.
When it comes to Udemy courses, never pay the asking price. There’s always massive discounts or voucher codes just a google away.
Learn to Code by Making Games - Complete C# Unity
UnitySteer is an open-source MIT-licensed AI library of steering behaviors for autonomous agents, which can be used to have a group of agents reacting to each other such as flocks of birds, human crowds or animated particles.
DOTween is a fast, efficient, fully type-safe object-oriented animation engine for Unity, optimized for C# users, free and open-source, with tons of advanced features.
Lightweight but type safe CSV serialise/deserialise of objects.