A World Perfect for Servers with any Amount of Players.
The Diamond Quest is a fun and interactive game for both you and your players, and it doesn't really have to be for a server, either.

THE GAME (PLAYERS)-
100 Diamonds are hidden around the Great Mansion. Take the train from the Spawn Point to get there. Walk the bridge and read the rules.
You win a prize depending on the server. You may kill, but only to get the gems the victim has.
You can only walk back outside the house, once you have 100 Diamonds, and in the shack, adjacent to the mansion, will be a server operator waiting.

THE GAME (OPERATORS)-
In the Great Mansion are 100 Diamonds hidden in chests or puzzles (dispensers etc) and once the players have gone in, a moderator or operator should wait in the shack next to the entrance, where players will exit once they have 100 Diamonds. Check the amount of diamonds (a stack of 36 and 64) and then give a prize. After the prize has been given, disconnect all players and reload the map (or go in manually and replace the gems).