Create Cube Object
Rename to Player
Components - Physics - Rigid Body


Press play, object will fall down
Create 3D Object, Plane

Scale to 10 x 10

Create C# script called player
Attach to player object

public class Player: MonoBehaviour {
	public float speed = 6;
	RigidBody myRigidBody;
	Vector3 velocity;
	void Start(){
		myRigidbody = GetComponent<RigidBody> ();
	}

	void Update(){
		Vector3 input = new Vector3 (Input.getAxisRaw("Horizontal"), 0, Input.GetAxisRaw("Vertical"));
		Vector3 direction = input.normalized;
		velocity = direction * speed;
		}

	void FixedUpdate(){
		myRigidBody.position += velocity * Time.fixedDeltaTime;
	}
}


Create more cube objects, with different materials so that you can differentiate the colors
Apply to platform, and cubes
Press green y axis

Create obstacles, change the scaling

press play

If you want to lock rotation, go to Rigidbody in side menu, Constraints, and check x y and z for rotation