God beats the first Cthulhu, but not the second. Zeus looks and behaves pretty much like God. The game doesn't seem to know what Poseiden is, but Phoboscidean turns out to be some kind of woolly mammoth.
And it turns out that Tanks have unlimited ammo and kill ANYTHING ...except Vampires! Vampires kill _everything_. A Vampire can kill Cthulhu. A Vampire will turn most human types into some kind of Banshee, including God!
The only things i've discovered so far to kill Vampires are, of course, holy water and garlic. Luckily as long as you're in a Tank you seem to be indestructible (except presumably from Floods) so you've got plenty of time to figure out what to do. Likewise with a Bomb Shelter, except you can't drive a Bomb Shelter or kill people with it :)
Also, once i've created and placed Quicksand i can't figure out how the hell to get rid of it. I can't even pick it back up again and put it in the trash! =P
Also also, flying carpets and magic brooms really suck. They don't get you any higher than a jet pack, and the flying carpet at least seems to have an unfortunate tendency to drop me through the floor.
Finally, the Fan seems to be one of the most useful tools in the game :)