I am a 25-year-old Australian. When I was very young, about 11 (so in 1996 or so) I played The Mathematical Reflex Test by Jason Lowe. More info here:
I remember sending him a letter asking him how to get past one of the levels, and he wrote back to me. (Snail mail, of course!) I remember Jason was also Australian, and lived in Adelaide at the time. Does anyone here know his whereabouts, or is in contact with him?