Unlocked

I realize that this might bring even more... how to say?... arguement about unfairness. But I was looking through similar games to this one, both multiperson and not and I realized that out of the items buyable or unlockable until you have reached a certain level. This could also mean levels would be worth more (although I realize most of those comments are just off this context but still) Anyway so I figure once you get to a certain level you can buy a new array of stuff in the shop. That could also works for achievements you could get, that way you would have a new 'mission' for each level. The other way it could work is that you got something special or a choice of gifts for leveling up. So maybe one or two 'special' races. Now I am most certainly not suggesting anything enormously powerful, just a new combination of bonuses and whatnot that you could only get at a certain level.