I shall now list a few suggestions, but if YOU don't like one or a few of these then just make a post, or if you have one of your own.
1. Under world tab it can say if you're hiding or not to help those players who's internet is slower
2. Admin can get "Earthquake" property which unhides everyone and freezes them for 2 or 3 secounds
3. A few more items
4. The ever popular trophies
5. Trophies rewarded with rare and mystic chars.
6. Contests to which you can win something
7. Collectable items you gain from Trophies
8. More stages just to be exciting, but maybe a stage with "gravity"
9. Somehow get users involved in the forum more, and make forum more active.
10. Make a part of the forum that only gm's can see.
11. Make "GM talk" on the game so as not to disturb the players.