Diablo 3 will ship with an Achievement system, noting how many monsters you kill, what types you encounter and the like. Titles and other effects can be received through killing especially many monsters, using specific items etc.
Blizzard Level Achievement
The Diablo 3 Achievement system will be an account-based system tied to a player's Blizzard Account ID, the purpose of which is to track achievements of all three major games: World of Warcraft, Starcraft 2 and Diablo 3. When combining all the games together, a score dubbed "Blizzard Level" is gained.
References
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