I think how to display/prove that players have already got the achievements is an important thing too.
I have some idea, which is putting the achievements before the players name, for example:
Before After
Tony1509 [Best player]Tony1509
However, changing achievements is a technological problem.
Making achievements an item to use and after using will erase the previous one is a method, I think.
Another display method is to make an achievements display board, which containing information about how to get the achievements and which achievements has already achieved. (Sorry.. my word bank is small XD)
Some achievements can be hiden as "hiden achievements" which may have more awards.
About the awards, I prefer status such as strength, attack and attack speed, defence etc..
P.S. I just know how "achievements" spelled... Well I am from other country and also my English isn't that good... Please forgive my bad English standard.
