Unity - Programming Guidelines

Basic PR Rules

No Scene should have any Console Errors
No PR should contains files from an unrelated branch
Double-check your PR after you open it, to ensure that it doesn't have unexpected files
Every new feature should be tested in the Unity Editor

All editor fields should be private, camel-cased [SerializeField] private Type name = default
All properties should be Pascal-cased public string Name { get; }
All methods should be Pascal-cased public void Execute()
Don't use code regions

Don't use Lists. Only use Arrays and Dictionaries.
Don't use Linq, since it results in boxing elements and impacts Garbage Collection
Allocate arrays during Awake/Enable phase. Avoid creating arrays during the Game Loop

Don't include constructors in any MonoBehavior or ScriptbleObject
Explicitly assign a value to private SerializeFields to prevent C# warnings, even if you must assign it to null
If an object should be configurable from code, use a method public void Init(...) instead
Every PreFab and ScriptableObject should have sensible defaults wired in
There should never be any unused methods in code (such as Start/Update)
There should never be any Unity-generated comments in code
All Scriptable Objects must be able to be created in the Editor
Every script should be small and single purpose

Everything in a scene must be composed of nothing except high-level PreFabs
Every PreFab must be able to be dropped into a new Scene and "just work"
No Prefab may have any overrides when used in a Scene or another PreFab
PreFabs must have all of their required connections set in the Editor
ScriptableObjects are safe connections, since the are Global Singletons
Children elements are safe connections, since they exist within the current hierarchical
PreFabs must not have more than 8 immediate children
When a generic PreFab is available for an element, use the generic PreFab instead of a custom one (buttons, for example)