campfire/Assets/Scripts/GameState.cs

using UnityEngine;

[System.Serializable]
public enum State {
    Playing,
    Paused,
    GameOver
}

public class GameState : MonoBehaviour {
    public State Current = State.Playing;

    private void Update() {
        if (Input.GetKeyDown(KeyCode.Escape)) {
            switch (Current) {
                case State.Playing:
                    Current = State.Paused;
                    break;
                case State.Paused:
                    Current = State.Playing;
                    break;
            }
        }

        Time.timeScale = Mathf.Lerp(Time.timeScale, Current == State.Paused ? 0 : 1, 6f * Time.unscaledDeltaTime);
    }
}