10.000 hours on a single game make you a great gamer of that game. While 10k on many games can be mean nothing sadly because you can play casually hundred of games.
Reach 10.000 hours with a game mean really devotion, playing everyday only that game for 3 to 8 years, its a big achievement for a gamer as the sacrifice of IRL, not having friend, living with parents, not knowing sex, sometimes even not step outside home, living behind a monitor.