It is entirely dependant on the game, never mind the genre.
Like you said for Mario Kart, mastery would surely be the ability to get a 3 star ranking in all cups easily, as well as beating all the hard ghosts and having at least 9000 (if not 9500) in the online vs and battle mode.... that could take weeks upon weeks upon weeks.
You cannot put a number to this for gaming in general.
by your definition I am not sure there are many games I have mastered... Timesplitters 2 comes to mind here as I cannot finish the hard mode, and I haven't got all platinum/gold medals in the mini game bit.
Goldeneye I have completed all of it on 00 agent, but 1st of all it was probably 1 year after I bought it and second of all I had to get my friends brother (who is incredible at goldeneye and f-zero x) to complete Train on 00 agent because I just can't.
If you restrict it to platformers (which then at least means your time limits make sense (10/25 hour game thing)) and applied the same principle then presumably mastering would involve beating every level on every difficulty (if aplicable) in excellent times.
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Personally I would class mastery as when you feel "at one with the game", by which I mean everything is second nature, you can strafe around a corner in Goldeneye knowing exactly where to shoot and how many bullets to use, you can make perfect slides around busy corners in Burnout whilst changing gear and not hitting cars etc.









Leatherhat on July 6th, 2012 3pm. Vita sales:"3 mil for COD 2 mil for AC. Maybe more. " thehusbo on July 6th, 2012 5pm. Vita sales:"5 mil for COD 2.2 mil for AC."
