First of all, thank you Myself!
Secondly, I do have some Ideas for other Apocalypses. Here they are:
Desert Apocalypse:As Zale and Jester have suggested, this would be primarily focused on the drastic climate change from world-wide-ocean to world-wide-desert. Because I want a decent scientific explanation for where all the water went, should you choose to make this follow the global flood, I suggest that there were huge underground caverns that had passages opened to them by a seismic catastrophe and sucked up most of the Earth's water, fresh or not. There could be a few oasis's and a few small cities, the explanation for their source of water being on a leak from the underground cavities or being situated above one of the cavities and being able to drill only enough water to survive off of. If you wanted there could even be water bandits and huge desert creatures.
Primeval Apocalypse:This could come after the global desert apocalypse, should you choose so. This would be after the underground caverns had ruptured taking with it huge quantities of fresh water as well as much oxygen. These extra nutrients could cause the world's flora and fauna to grow to huge proportions. This would be almost prehistorically themed.
Ancient/Advanced Civilization Apocalypse:The one that could come after global flood or either of the above. After several apocalypses the human race has actually advanced their own technology, discovered and found out how to utilize some paranormal phenomena, and discovered thee churned up remnants of ancient advanced civilizations causing a reinventing of the world. This one would deviate from the other apocalypses in how instead of a mainly ecological or viral catastrophe the problem is now in civilization itself because with such a radically different culture and technology people are going to war and things are changing quickly. In this common people would have more advanced technology, but not the futuristic kind. Instead their technology is mostly based off of ancient advanced civilizations such as those described in indian epics. Magic use would be prevalent and aerial vehicles, such as various vimanas, would be used in combat. This specific apocalypse would pit us against people who could wield magic, albeit only minor in most low level cases, and posses advanced weaponry, though none of the extreme weapons found in hindu mythology.
Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn