LibGit2Sharp VS FlaxEngine

To use it as an API on windows you might want to go with a C# wrapper. libgit2sharp

You might want to leverage something like libgit2 if you store that data in a unique location. After you commit changes to your data, you can find the patch differences in the file. Then store the commit hash and set up communication that wakes up when the hash changes. When the commit hash changes, you send just the patch changes to the clients which can apply them to their local copy.

libgit2sharp to work with git repositories in .NET https://github.com/libgit2/libgit2sharp

Is it something you could possibly achieve with git? - https://github.com/libgit2/libgit2sharp/

Currently, my plan is to use LibGit2Sharp to do almost all the logic, and use System.IO to manage the local files. Problem is: LibGit2Sharp documentation is very sparse and hard to read.

Flax (MIT/C++) https://github.com/FlaxEngine/FlaxEngine

For 3D games, check out the engine: Stride Engine or Flax Engine.

Flax Engine: C# and C++, Global Illumination system, Visual scripting, Full Source Code Available, 4% royalties after $250,000 (threshold is per quarter, not all time). The engine honestly looks really good, so it could be worth taking a closer look, but does lack tutorials.

It sounds like you're asking them to just remake https://flaxengine.com. (Minus ECS)

As the title says, what are people's thoughts on Flax Engine. (Link for anyone who hasn't heard of it)

Flax (4% royalty after 100k revenue) looks to be the most Unity-like, and seems to be pretty polished, if also new and lacking features. That's all I know about it so far. Its pricing model is similar to Unreal's and, like Unreal, it's source-available (but not truly open-source).