public void Solver_OnCollision(object sender, Obi.ObiSolver.ObiCollisionEventArgs e)
    {
        var world = ObiColliderWorld.GetInstance();

        foreach (Oni.Contact contact in e.contacts)
        {
            ObiColliderBase collider = world.colliderHandles[contact.other].owner;
            if (collider != null)
            {
                if (collider.tag != "Ground" || collider.tag != "Walls")
                {
                    if (contact.distance < 0.01)
                    {
                        ObiSolver.ParticleInActor pa = solver.particleToActor[contact.particle];
                        Slime s = pa.actor.gameObject.GetComponent <Slime> ();
                        switch (collider.tag)
                        {
                        case "Food":
                            for (var f = 0; f < s.food.Count; f++)
                            {
                                if (s.food[f] == collider.transform)
                                {
                                    if (s.testingFood[f])
                                    {
                                        s.testingFood[f] = false;
                                        s.AddReward(1f);
                                        break;
                                    }
                                }
                            }
                            break;

                        case "Enemy":
                            s.Death();
                            break;
                        }
                    }
                }
            }
        }
    }