Wouldn't it be nice to "seal" the Awake function?

[neo-mashiro]

protected virtual void Awake() {
    if (_instance == null) {
        _instance = this as T;
        DontDestroyOnLoad(gameObject);
    }
    else {
        Destroy(gameObject);
    }
}

The Awake() function is the key part to make the derived singleton class persistent across scenes and prevent duplicates, but it is marked as protected virtual, so that one could accidentally override it but forgot to add the base.Awake() call, which would then break things apart, and it's hard to debug...

I think maybe we can improve by doing sth like this?

private void Awake() {
    if (_instance == null) {
        _instance = this as T;
        DontDestroyOnLoad(gameObject);
        Initialize();
    }
    else {
        Destroy(gameObject);
    }
}

protected virtual void Initialize() { }

[hasanbayatme]

Yeah your point is completely valid, I'll add this coupled with #2, let me know if you have any other suggestions!

[hasanbayatme]

Added Init method that is called on creation of the instance or reusing the instance from existing object in the scene from Awake method at e902a9f