Yeah a stall is when the air flow over the wings can no longer 'hold on for the ride' so to speak. Just as the air flow seperates from the body of the wing (because its just at too much of an angle) the aircraft suddenly looses all that lift, and the nose drops. Well-behaved forgiving aircraft you can really feel this coming, as the seperation of the airflow is gradual. The dangerous ones that 'bite you' typically the airflow will seperate suddenly en masse...Laminar wings are prone to this.
Also in the in-between realm of a seperating airflow, you get buffet, wobbling and shuddering.. Gl with your game.