YouTubers! Please link to the release video instead of this thread!
Calamity 4 requires Minecraft v1.7.4 and is recommended for 10 players (5 vs 5).
Calamity is a two-lane attack/defend PVP minigame.
The objective is to reach the other teams bastion and run the machine for one minute. You run the machine for one minute, and you win the game. Players organize themselves into different lanes (a 2/3 split is standard), and attempt to push the lanes to get to the other teams machine.
There are a lot of absolutely fantastic elements to the map, too numerous to explain here.
Calamity has been featured by Mindcrack, The Yogscast, and many other very prominent YouTubers.
Additional screen shots (imgur album)
Developers journal (imgur album)
Version 4 - Mediafire