I use Chess, ‘clinically’.
It gives me extraordinary information about a child. I assess short term memory, long term memory, attention to detail, analytical skills and performance of logical operations, and all the while kids are having fun.

I see children learn the wisdom of impulse control. I see children gulp as a figure is taken. I see children understand and appreciate the occassions I ‘cut them slack’ (let them take back a move). I see them making fine moral distinctions as they decide ‘their win’ doesn’t count (I cut them slack). I see ’symptoms’, a whinyness that I ignore, an assertion that ‘they can’t do it’ when I know they can. 

I see them sit up straighter as their skills improve. They know their skills are improving. I may or may not comment upon it as the most important thing is their own increasing sense of accomplishment. They, by virtue of their own accomplishment, feel better about themselves. Parents report, they are observably ‘calm and collected’ after our meetings and that ‘they seem to behave more respectfully towards others’.