Kerbal Space Program

Building KSP with additional Unity packages already available in the package manager would help modders.

• TextMeshPro - much easier to build the UI in Unity Editor and export the scripts in an assembly since the resulting assembly would reference UnityEngine.TextMeshPro, either built directly from the Unity editor or with a separate compiler. There would be no more need to tricks like exporting UI assets with Text components which would be replaced with TextMeshPro components on load.

• Burst and Mathematics - this one is a bit tricky since standalone clients can only use AOT compiled Burst jobs which seem to be loaded from a single hard-coded named .dll (Data/Plugins/lib_burst_generated.dll on Windows). However, using Burst can yield massive improvements in numerically heavy operations by utilizing SIMD instructions and cache coherency in arrays.

• Entities when it is production-ready - just look at Factorio and how iterating over entities close to each other in memory improves performance over the current OOP approach.

This is already possible by building a Unity project and copying the output libraries into GameData or Data/Managed folders but mods would have to distribute them in order to work even though the libraries are the same.