About the Yaffaif category

Explore a fantasy world that seems intent on transforming the player into something else…

Project Website

Yaffaif is an adult text-adventure or text-based role playing game in a “fantasy” setting (however, it has a graphical interface that tries to eliminate the main frustrations of textual input. So no endless typing input (unless that’s your thing - in which case enjoy the auto-complete of words).


The main theme is slow transformation, of which weight gain is a very significant part. One of the reasons for buiding a bespoke engine is to provide the necessary detailed character descriptions. The main plot is advanced by compleing various quests and in general there will be a couple of ways to do this: one accepting transformations or weight change of the player character, and a (usually) more difficult or grindy way where you don’t. A key design choice is that transformations have consequences - they aren’t just modifications of the character’s description. It is also open-world too; there’s no necessity to complete the various quests. If you want to settle down, romance a partner, end eventually raise a family you could do that too.

Also included:

  • anthropomorphic (furry/monster) NPCs and transformations
  • voluntary (or at least avoidable) transformation (weight, species, size, gender)
  • clothing bursting, furniture breaking, getting stuck, and immobility
  • turn-based combat (in the style of OSRIC/old school DnD)
  • turn-based sex (m/f, m/m, f/f, and more)


The starting species, gender, and appearance of the player can be customised before you begin playing.


I’m going to try and consistently use the following tags in this board to make things easier to find and navigate:

  • Release: Whenever a new version of the game comes out (more below)
  • Dev-note: For any development discussions - a dev blog if you will
  • Bug: Any problem with the game - please use this when reporting bugs!


Releases happen as and when there’s something new that can be experienced playing the game. A lot of the work is happening under the covers, deep in the engine. While this makes things easier (or possible) to move forward, and give me a sense of satisfaction, unless they make the game play differently they don’t count as worthy of a release in my book.

Things have been very difficult in the last year or so and progress is erratic. Yaffaif is a huge project, and you will have to bear with me.

Can I load an old save in a new release?

The short answer is no. The slightly longer answer is, yes, currently it will probably let you (but may not) however any new additions to the content won’t be present and you will be playing the game as it was in the earlier release, just with fewer bugs (hopefully). Once things are more stable I’ve plans to make save games migratable between versions.

Will it include … ?

Oh my. I’ve a fair few things roughed out in terms of plot and what the PC might have to go through and the engine is capable of more than is currently exposed in the game. On the whole it will probably include it if I enjoy writing it, and unlikely if I don’t. On that basis any kind of scat or watersports are probably not going to happen.

Expect the number of species included to grow as the game develops.

Underage partners won’t be included as that would just be plain illegal for me to do.

Can I write a (sex) scene?

No, not really, because the engine doesn’t work that way. “Scenes” are procedurally generated from small chunks of text and are selected based on the many variables that define the characters involved. Given the transformational nature of the game it would be next to impossible to write a scene to cover every possible pairing. Also the game has a concept of sexual expertise; advancing actually changes the way things pan out so you won’t always get the same scene - practise makes perfect!

However if you would like to craft some of the little bits of text please get in touch.

How else could I help?

Play the game, find bugs, typos, let me know about them (see Bug reports (revised)). Tell me what you like and don’t like about it. Share tips with other players.

If you would like to support the development you can do so on Patreon where there are a number of different rewards, including walk-throughs, early access, developer documentation, and more. I’m not thinking of any kind of cheat mode (it’s already in there: see Debug Mode). I’ve set up a tip-jar on Ko-fi if Patreon isn’t your thing, but you’d like to encourage me financially. The public release of the game will always be free to play though.


I don’t know if I’m supremely stupid and don’t recognise that I’m doing something terribly wrong, but I’m trying to run it and following all the steps on the website, and yet it won’t open.

so I look in the mine but can’t find the brother. Am I missing something?

Hey, I don’t track this thread so I didn’t see this sooner. Not that I’m tied to the game in any official capacity, but I can try the basics of helping.

  1. Do you have the latest Java Runtime Environment (JRE) installed? www.java.com

  2. You’ve downloaded the GameFX2.zip file and extracted everything? (You can’t just use Windows Explorer to open the folder and run it.)

  3. File structure inside the GameFX2 folder should be:
    A folder named ‘lib’.
    A file named GameFX2.
    A compressed folder named GameFX2.src.

If you’ve got anything else in there, there’s a chance you extracted things you shouldn’t have, intentionally or otherwise.

If you have issues figuring out how to navigate through the Command Prompt, you can download this file: https://drive.google.com/file/d/1HCwG0JVOb4hRGUjsuhBznTPXmh_4kQRh/view?usp=sharing and put it in the GameFX2 folder alongside the things that belong there. Double click it to run the game.

No sir you are not. That quest was put in as an unfinished ‘hook’ and will be completed in a later update.

@Thatrantingmadmanofy: did you get it working following @Schattenjaeger’s instructions? Sorry I’ve been away for a few weeks.

I downloaded the file he sent, since I couldn’t manage to get it working otherwise.