Best way to implement achievement system for android game
I currently try to implement achievement system for my game, but can't find a better way to realize some complex ones like: the player has collected x coins, complete level with time least than x seconds, Kill over x enemies etc... Could you share your experiences please? 

Secondly, Why don't we just implement achievement system as local only instead of using server like Scoreloop or OpenFeint? Or put it in another way, What are the advantages of using server for managing player's achievement?
Best way to implement achievement system for android game
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I currently try to implement achievement system for my game, but can't find a better way to realize some complex ones like: the player has collected x coins, complete level with time least than x seconds, Kill over x enemies etc... Could you share your experiences please? 

Secondly, Why don't we just implement achievement system as local only instead of using server like Scoreloop or OpenFeint? Or put it in another way, What are the advantages of using server for managing player's achievement?