Game Event definitions for Drumpf Flinger 9000 (a Unity 3D game)

Announcements.cs

using UnityEngine;

/*
  You could name this class GameEvents or whatever you want. I chose Announcments because
  it doesn't conflict with any builtin Unity class names. I can just type 'ann' and my IDE's
  auto-complete takes care of the rest.
*/
public static class Announcements
{
  public static class Camera
  {
    public static void ToLaunch() { if (OnToLaunch != null) OnToLaunch.Invoke(); }
    public static event Action OnToLaunch;
    
    public static void AtLaunch() { if (OnAtLaunch != null) OnAtLaunch.Invoke(); }
    public static event Action OnAtLaunch;
    
    public static void ToSpawn() { if (OnToSpawn != null) OnToSpawn.Invoke(); }
    public static event Action OnToSpawn;

    public static void AtSpawn() { if (OnAtSpawn != null) OnAtSpawn.Invoke(); }
    public static event Action OnAtSpawn;
  }

  public static class Game
  {
    public static void Start() { if (OnStart != null) OnStart.Invoke(); }
    public static event Action OnStart;

    public static void Over(WallSegment brokenWall) { if (OnOver != null) OnOver.Invoke(brokenWall); }
    public static event Action<WallSegment> OnOver;
  }

  public static class Projectile
  {
    public static void Spawn(Projectile newProjectile) { if (OnSpawn != null) OnSpawn.Invoke(newProjectile); }
    public static event Action<Projectile> OnSpawn;

    public static void Launch(LaunchDirection direction, Transform lookAtTarget) { if (OnLaunch != null) OnLaunch.Invoke(direction, lookAtTarget); }
    public static event Action<LaunchDirection, Transform> OnLaunch;

    public static void ImpactWall(Vector3 position, Vector3 normal) { if (OnImpactWall != null) OnImpactWall.Invoke(position, normal, 0f); }
    public static void ImpactWall(Vector3 position, Vector3 normal, float velocity) { if (OnImpactWall != null) OnImpactWall.Invoke(position, normal, velocity); }
    public static event Action<Vector3, Vector3, float> OnImpactWall;

    public static void ImpactGround(Vector3 position, Vector3 normal) { if (OnImpactGround != null) OnImpactGround.Invoke(position, normal, 0f); }
    public static void ImpactGround(Vector3 position, Vector3 normal, float velocity) { if (OnImpactGround != null) OnImpactGround.Invoke(position, normal, velocity); }
    public static event Action<Vector3, Vector3, float> OnImpactGround;

    public static void Dead(Projectile oldProjectile) { if (OnDead != null) OnDead.Invoke(oldProjectile); }
    public static event Action<Projectile> OnDead;
  }

  public static class UI
  {
    public static void DragStart(Vector2 position) { if (OnDragStart != null) OnDragStart.Invoke(position); }
    public static event Action<Vector2> OnDragStart;

    public static void Drag(Vector2 position, Vector2 direction) { if (OnDrag != null) OnDrag.Invoke(position, direction); }
    public static event Action<Vector2, Vector2> OnDrag;

    public static void DragRelease(Vector2 position, Vector2 direction) { if (OnDragRelease != null) OnDragRelease.Invoke(position, direction); }
    public static event Action<Vector2, Vector2> OnDragRelease;
  }
}

ExampleUsageBehaviour.cs

using UnityEngine;

public class GameCamera : MonoBehaviour
{
  private void OnEnable()
  {
    // Add handlers for game events...
    Announcements.Projectile.OnSpawn += Projectile_OnSpawn;
    Announcements.Projectile.OnLaunch += Projectile_OnLaunch;
    Announcements.Projectile.OnImpactWall += Projectile_OnImpact;
    Announcements.Projectile.OnImpactGround += Projectile_OnImpact;
    Announcements.Projectile.OnDead += Projectile_OnDead;
    Announcements.Game.OnStart += Game_OnStart;
  }

  private void OnDisable()
  {
    // Clean up handlers for game events...
    Announcements.Projectile.OnSpawn -= Projectile_OnSpawn;
    Announcements.Projectile.OnLaunch -= Projectile_OnLaunch;
    Announcements.Projectile.OnImpactWall -= Projectile_OnImpact;
    Announcements.Projectile.OnImpactGround -= Projectile_OnImpact;
    Announcements.Projectile.OnDead -= Projectile_OnDead;
    Announcements.Game.OnStart -= Game_OnStart;
  }
  
  // All your handling code down here...
}