https://github.com/Pierrot-ongit/RealTimeStrategy-Multiplayer/tree/master/Assets/Scripts
Also made in Unity. A short RTS, with a single map, and few units and buildings. The essential part is that is multiplayer, with an host and others players joigning the game through a lobby.
The library Mirror was used to handle it, and I was able to learn some fundamental multiplayer development principles such as synching variables, remote procedure calls (RPCs) and writing server authoritative logic.