I been thinking, after wololo kingdoms, what is the only thing voobly still dont have...
I dont know how voobly works but i think if it uses mysql there is possibility to make achievements system for voobly
There is already game saves connected to websites
-1000 kills per game, 50 razes, king of the hill, 15 games win streak and things like that,
and mabye we will have even more player playing on voobly

I would say unnecessary, reason why is because everyone would have the achievement so it's not really a achievement.

hmm, but take steam for example, not all players will be able to have all achievements maybe pro players but not all players, make it harder to unlock

All the achievements you listed can be accomplished just by playing 1v1 vs a friend, or anyone, though. Are achievements like "enemy of saracens" "played 50 games online" really necessary or that appealing? They have very little value to them

Anyways, just my opinion based on similar reward based games I played in the past.