Around 2.35am GMT+1 (in 5 1/2 hours from creation date of this posting) the server will recall all players (20 minutes ahead warning will be displayed) and restart. After that, Halloween is live and costumes can be worn again. =)
Description for those who don't know the event yet:
Townspeople will actually give experience (!) but also have a fear-causing touch attack. They can't really harm you, though.
Randomly, the Great Pumpkin will appear on dungeon levels, either with low or medium or high amount of hit points, depending on the location.
The event is aiming at intermediate-level characters. The pumpkin always spawns shallower than dungeon level 40. Players who are too high level (above 35 on main, above 40 on RPG) will not be able to hunt him, for the others he will still be tough and might require teamwork. The Great Pumpkin does not cause any damage but still has a few annoying spells at its disposal.
The Great Pumpkin is level 127 and therefore can drop any item in the game, and usually drops very good. Please share fairly.
When a player defeats the Great Pumpkin, everyone will get a message about it. The Great Pumpkin will start randomly respawning again some time later.
enjoy!