The Underworld: A Transformation Game

A text adventure where you’re forcefully transformed into a variety of feminine anthro/furry/monstergirl forms!  Just yesterday, you were a human male living in a modern town.  Now you’ve found yourself trapped in The Underworld and your body is nothing like it used to be.  Who is behind these changes, and how will you change back?  The longer you’re down here, the more you start to enjoy your new life…

This is a transformation text adventure with a rich story — it’s already longer than a novel, and continues to develop.  You’ll meet a wide cast of characters across the three factions that each have their own ideology about how to deal with people different from themselves. Your actions will determine which faction achieves victory, and by extension, the fate of humans and hybrids alike.

If that’s not enough, the game also includes a wide range of modding features to add your own enemies, items, clothing, and even custom transformations.

This game deals with mature subject matter, including erotic content such as: furry transformation, monstergirl transformation, male to female (MtF) gender transformation, oviposition, lactation, and much more.  As such, this text adventure game is only for adults!

(No download required, runs in browser)

The Story

In 2019, a virus was discovered that caused extensive mutagenic effects in the general population.

SkyCorp Global’s Research Division was the first to identify this virus, designating it VIR-819.  The infection was pronounced and forever changed anyone it touched.  Victims often underwent significant changes to their libido, frequently becoming sex-crazed.  These glandular changes sometimes caused dramatic shifts in patient’s height, weight, even their gender.  In the most extreme cases, the infected lost their very humanity itself as they devolved into monstrous animal-human hybrid creatures.  It was clear that dramatic steps needed to be taken to protect our way of life.

This contagion spread like few ever had previously.  With no cure in sight, the following year SkyCorp was awarded the Department of Defense contract to create a quarantine zone for the infected.  The quarantine zone was hastily constructed, and with close partnership from the National Guard, all infected were forcibly relocated.  To this day, SkyCorp continues the administration of the quarantine zone.

Due to this zone being a collection of largely underground facilities that were reappropriated for containment, the project has been colloquially referred to as ‘The Underworld.’  While uninfected citizens are technically permitted to visit The Underworld, it is heavily discouraged due to the risk of exposure.  Still, occasionally a citizen will need to enter regardless.  In that situation, we can only pray they will return human — or they’ll become a permanent resident themselves.

(This story was originally written in 2014 and is not intended as a direct reference to real-world events)


“As someone who only cares about TF (Transformation), Underworld’s pretty damn good. In most TF games, TF’s are more or less just a cosmetic option, whereas in Underworld, you actually get to explore the implications and consequences of TF’s, which have actual mechanics attached. It’s great, and I’m kind of frustrated that nobody else does this.” — Shin Majin

“This game has truly been an enjoyable play through, the story is enjoyable, game itself is cross-platform because of flash, and the current variety of scenes and what can be done is really enjoyable.”

“I love this game so far! If I had two sentences to review this game and encourage others to give it a shot, it would be these two:
I used to be quite disinterested in slug girls.
I am now utterly and wholly interested in slug girls.” — Railby

“I can already tell it’s a great game . . . you obviously put a lot of time into making this masterpiece, keep up the awesome work” — Rena

‘I can never get past the Dino chapter because I just want to stay there forever.” — Former human, now a dino slut

(No download required, runs in browser)