NOTE: There is a known issue with the most recent entries having screwed-up information and links. Some databases are out of sync and we haven't been able to fix it yet.
It is called Citadel for two reasons. One is because it is on the level map which is called Citadel, and second is because its a castle. Now your job is to clear it from those nasties and zombies so try it out and save the Citadel.