Pinti Land: Realm of Plague is my game for Series Swap Day 5 where I, if you hadn't already guessed, got the Pinti Land series. Unfortunately there wasn't a whole lot of information to go by, so I used the "YoshiEgg method": just do an incredibly creepy spin-off.
In this particular instance, my main inspiration is the indie game Eversion which you can find for free somewhere on the internet, or get the higher-res version with achievements on Steam for a small monetary investment. I won't spoil it for you, but it's a pretty cute little platformer that you should definitely try (preferably alone at night in the dark with headphones on).
Bsaically, Pinti Land: Realm of Plague is about Pinti's girlfriend Penti being kidnapped by an extra-dimensional Cthulhu-esque being, and taken to the eponymous Realm of Plague. It turns out Dr. Dastardly thought he would be able to control the unspeakably horrific creatures if he summoned them, but it didn't work and now their world is going to be consumed by bloodthirsty R'lyehzoids.
Thankfully Dr. Dastardly manages to use the same technology he used to summon them to open a portal for Pinti to go through to rescue Penti (and you know, worst comes to worst his mortal enemy has just entered an alternate universe full of Eldritch abominations).
The game otherwise plays like a normal platformer, with all the same power-ups and abilities Pinti had in his first game. The difference is in the new enemies and setting, which are based very largely on the Floodverse Mythos, which I tend to use a lot because it's combination of Lovecraftian horror and penguin-related shenanigans is quite cheerful and horrific at the same time. (Also if it's regarded as canon it can help cement Pinti Land into Fantendoverse canon because JIM's got his robotic arms wrapped up in everything, so the Floodverse serves as a convenient point of reference for canonicity).