Rat Overflow is a deceptively cute rat breeding simulator about genetics, glory, and having way too many rats.

Breed fancy rats with a realistic color genetics system, show them off in competitions, and try to keep track of your ever-growing colony. Pick your pairings carefully — or don't — and watch the pups grow into champions, beloved pets, or delightful genetic surprises. With thousands of possible rat appearances driven by real inheritance mechanics.

Start with humble stock, outcross from five quirky NPC breeders — each with their own color specialties and personalities — and build bloodlines that dominate the show circuit. But be warned: Rats breed fast. More pups are on the way. They're always on the way.

SHOW THEM OFF

Enter your best rats in shows against rival breeders, win championships, and level up to unlock new breeders with new color varieties and better genetics.

REAL GENETICS, REAL CONSEQUENCES

Over a dozen genetic loci control color, markings, health, and conformation. Siamese, Russian Blue, Dumbo ears, Rex coats — it's all in the genes. Breed strategically, or discover what happens when you don't.

DRESS TO IMPRESS

Buy outfits and accessories to style your rats for photo ops. Express yourself. They're your rats now.

FEATURES

• Realistic genetics with 14+ loci and thousands of color/pattern combinations

• 5 NPC breeders to unlock, each with distinct specialties

• Multi-tier show system with rival competitors

• Health and conformation genetics — longevity and show success are inherited

• Pastel retro aesthetic with pixel art and a Windows 98-inspired UI

• A gentle but persistent sense that you have too many rats

About AI use in game development

The game's code is written with significant help from AI.

Some text in game, as well as text on the store page is written with AI assistance.

All graphics in the game are and always will be painted and edited by me without any use of generative AI. Same goes for all graphics on the store page and other marketing.