In this study, a simulation model is built to study the body water regulation and its disorders by focusing on the fundamental feedback mechanisms in the normal and disease physiology. This model is then extended to include related therapeutic interventions of the most common body fluid/electrolyte disorder, namely water intoxication/ hyponatremia, and a game version is produced to test the possible effects of a given set of treatment options on a simulated patient. The model is shown to adequately reproduce the changes in the body fluid balance not only in a normal person as a result of a given disturbance, but also in a hypothetical hyponatremia patient. The interactive simulation game version of the model proves to be a useful experimental platform to describe changes known to occur after administration of various pharmacological means. The aim of the treatment is to increase the extracellular sodium concentration safely by reducing the body water and replenishing the sodium deficits. Game results demonstrate that hypertonic saline should be given carefully concurrently with drugs that increase urine flow, and antidiuretic hormone-antagonists happened to be superior over diuretics. The model and the game version constitute an experimental laboratory for a closed-loop therapy approach to hyponatremia.