My first idea for halfbakery - what a site - best laugh I've had in a long time (custard speed bumps - lol!)
That said, given the recent price drop in digital camera technology, a toy gun could be fabricated with reasonable economy such that the lens of a low-end digital camera faced out of the
barrel, the electronics for which I suppose could be in the magazine or handle or elsewhere...
As youngsters trade shots with said guns in mock gunbattles, the images are recorded (with superimposed crosshairs!) for post-conflict review and scoring.
Just plug AV cables or USB into the gun and check out the
marksmanship on TV or PC! Clear the memory, and off they go again.
Could have real-world (non-toy) application also for target practice or battlefield documentation... probably baked.
Note I'm not crazy about children and toy guns either, but boys will be boys, and this would not shoot darts that put eyes out etc...