Oyster online history "game"
 

(And I'm a bit reticent at the idea of spreading one's journey history
far and wide, but then again I'm probably a bit old-school in my take
on such things - 'the kids' are quite happy to bare all and sundry
online...)

It also has quite an interesting flash visualisation of your journey
history.

(You will need to have an OEP permanently loaded to see journeys
completely within any Travelcard zones)