Those suffering from ADHD find relief in medication, but the medication only relieves symptoms; it doesn't treat them. One summer camp for children with ADHD offered training in social skill and attention and awarded children points for following rules. The children had to compare their points at the end of each day to determine who the winner was, and were able to trade points for prizes at the end of camp. Attendees' ADHD symptoms lessened afterwards, even after the summer camp treatment had ended:
The key finding is that only the Summer Camp kids showed a reduction in the variability of their reaction times. This is significant because highly sporadic reaction times are a hallmark of ADHD, indicative of reduced self control. Moreover, only the Summer Camp group showed significant improvements in selective and sustained attention and the capacity to integrate information.
Token-based systems have been around at least as long as games, and they definitely share a reward structure. A reward as simple as a point can change our behavior. A video game that treats ADHD would be nice, but it looks like this treatment is already a kind of game.