- Attack of the 500' Tall Cock!!
A giant rooster is set upon the world to raze the planet, nuking everything it steps on, breathing atomic fire, and shooting lasers from its friggin' eyeballs!! Hearthlings can cower in fear and wait for the end, which will come 72 hours after the rooster is summoned... or you can FIGHT!! For those that fight back against the rooster and survive, and the H&H community as a whole is able to slay it before the 72 hours is up, those players get to keep their stats. Anyone who dies in honorable combat against Ultra-Mega Cock can inherit at the beginning of the next world with half of the death penalty... but if you just run and hide, no reincarnation. You make new character. - Survivor - Fire Island
Instead of water, volcanoes erupt and start filling the map with instant killing lava, shrinking the amount of land until only five tiny islands equaling half a macrogrid square are left, and then Thunder Dome rules apply. Last five standing get to keep their stats in next world. Everyone else just becomes future heartlings' gasoline... - Random Head Explosion
Life goes on like normal, and no reset is announced, until patient zero in a new bizarre disease reveals themeselves, as a random player's head suddenly explodes for no reason. After that, the devs announce the end of the world, and let pandemonium ensue, but first gives everyone +1,000,000 to all stats and skills, all thw while hearthling's heads randomly explode. You never know when your time is coming, but man, will the end times be fun until then.
If you have any other ideas for cool H&H apocalypses, add them here.