unity-cube-game/Assets/Scripts/PlayerCollision.cs

using UnityEngine;

public class PlayerCollision : MonoBehaviour
{
  public PlayerMovement movement;
  void OnCollisionEnter(Collision cInfo) {
    if(cInfo.collider.tag=="Obstacle") {
      movement.enabled=false;
      FindObjectOfType<GameManager>().EndGame();
    }
  }
}