The corruption comes from the Fortune Teller, she's the goddess of 'fertility'. Her and the Sea Witch (goddess of the fish folk) had a kerfuffle or something, causing them both to lose their powers somewhat. Those two and Justice, who's the god of the undead and the most powerful of the three, are playing more or less a pen and paper campaign. That's why the island is besieged by both the deep ones and the abomniations. IIRC the end goal of the game is to restore everything back to normal, the escape by ship route is just a way to end the game currently since it's not yet finished.
I do agree with the slow development. There's a lot of story lines and areas that aren't finisehd yet, we could use some more skills, weapons, spells and armors. Instead the rather lackluster updates during the last year or so forced people to start an entirely new game twice because saves from the old versions didn't work anymore. And for what? Mostly bug fixes, I think a new dancing minigame during a slavery route, one new outfit and a new passive skill. Oh, and you're able to equip panties and pads for your period now.
