Updated code to match video

DOTS_Pong/Assets/Scripts/GameManager.cs

 		main = this;
 		playerScores = new int[2];
 
+		manager = World.DefaultGameObjectInjectionWorld.EntityManager;
+
-
-		manager = World.DefaultGameObjectInjectionWorld.EntityManager;
 
 		oneSecond = new WaitForSeconds(1f);
 		delay = new WaitForSeconds(respawnDelay);
 	public void PlayerScored(int playerID)
 	{
 		playerScores[playerID]++;
-		for(int i = 0; i < playerScores.Length && i < playerTexts.Length; i++)
+		for (int i = 0; i < playerScores.Length && i < playerTexts.Length; i++)
 			playerTexts[i].text = playerScores[i].ToString();
 
 		StartCoroutine(CountdownAndSpawnBall());
 	void SpawnBall()
 	{
 		Entity ball = manager.Instantiate(ballEntityPrefab);
-	
+
 		Vector3 dir = new Vector3(UnityEngine.Random.Range(0, 2) == 0 ? -1 : 1, UnityEngine.Random.Range(-.5f, .5f), 0f).normalized;
 		Vector3 speed = dir * ballSpeed;
 

DOTS_Pong/Assets/Scripts/Systems/BallGoalCheckSystem.cs

 using Unity.Mathematics;
 using Unity.Jobs;
 
+[AlwaysSynchronizeSystem]
-    protected override JobHandle OnUpdate(JobHandle inputDeps)
-    {
-		inputDeps.Complete();
-
+	protected override JobHandle OnUpdate(JobHandle inputDeps)
+	{
-            .WithAll<BallTag>()
+			.WithAll<BallTag>()
-            .ForEach((Entity entity, in Translation trans) =>
-            {
-                float3 pos = trans.Value;
-                float bound = GameManager.main.xBound;
+			.ForEach((Entity entity, in Translation trans) =>
+			{
+				float3 pos = trans.Value;
+				float bound = GameManager.main.xBound;
-                if (pos.x >= bound)
-                {
-                    GameManager.main.PlayerScored(0);
+				if (pos.x >= bound)
+				{
+					GameManager.main.PlayerScored(0);
-                }
-                else if (pos.x <= -bound)
-                {
-                    GameManager.main.PlayerScored(1);
+				}
+				else if (pos.x <= -bound)
+				{
+					GameManager.main.PlayerScored(1);
-                }
-            }).Run();
+				}
+			}).Run();
-		return new JobHandle();
-    }
+		return default;
+	}
 }

DOTS_Pong/Assets/Scripts/Systems/IncreaseVelocityOverTimeSystem.cs

 using Unity.Mathematics;
 using Unity.Physics;
 
+[AlwaysSynchronizeSystem]
-		inputDeps.Complete();
-
-		Entities
-			.ForEach((ref PhysicsVelocity vel, in SpeedIncreaseOverTimeData data) =>
-			{
-				var modifier = new float2(data.increasePerSecond * deltaTime);
-				
-				float2 newVel = vel.Linear.xy;
-				newVel += math.lerp(-modifier, modifier, math.sign(newVel));
+		Entities.ForEach((ref PhysicsVelocity vel, in SpeedIncreaseOverTimeData data) =>
+		{
+			float2 modifier = new float2(data.increasePerSecond * deltaTime);
-				vel.Linear.xy = newVel;
-			}).Run();
+			float2 newVel = vel.Linear.xy;
+			newVel += math.lerp(-modifier, modifier, math.sign(newVel));
+			vel.Linear.xy = newVel;
+		}).Run();
-		return new JobHandle();
+		return default;
 	}
 }

DOTS_Pong/Assets/Scripts/Systems/PaddleMovementSystem.cs

 using Unity.Mathematics;
 using Unity.Transforms;
 
+[AlwaysSynchronizeSystem]
-		inputDeps.Complete();
-
-		Entities
-			.ForEach((ref Translation trans, in PaddleMovementData data) =>
-			{
-				trans.Value.y = math.clamp(trans.Value.y + (data.speed * data.direction * deltaTime), -yBound, yBound);
-			}).Run();
+		Entities.ForEach((ref Translation trans, in PaddleMovementData data) =>
+		{
+			trans.Value.y = math.clamp(trans.Value.y + (data.speed * data.direction * deltaTime), -yBound, yBound);
+		}).Run();
-		return new JobHandle();
+		return default;
-
-}
+}

DOTS_Pong/Assets/Scripts/Systems/PlayerInputSystem.cs

 using Unity.Jobs;
 using UnityEngine;
 
+[AlwaysSynchronizeSystem]
-		inputDeps.Complete();
-
 		Entities.ForEach((ref PaddleMovementData moveData, in PaddleInputData inputData) =>
 		{
 			moveData.direction = 0;
 		}).Run();
 
-		return new JobHandle();
+		return default;
 	}
 }