This only works on the new versions, not on the old iPhone version, sorry.
Create the following folder hierarchy:
- On Windows: "data/worlds/bres", in the game's folder.
- On the Mac: "The Quest/worlds/bres", in the Documents folder.
- For iOS and Android: "data/worlds/bres", anywhere on your computer, but see a later step.
Put an image in the innermost folder ("bres"), named "head01". The image must be a BMP file (so "head01.bmp"). It must be 128x128 pixels and 24 bit true color, without any extra metadata (like color space information). So a simple bmp file.
For the iOS: copy the "data" folder to your device, using iTunes (drag and drop the folder, "Add File..." won't work, sync after the copy).
For Android: copy the "data" folder to your device, into the "Android/data/hu.redshift.thequest/files" folder.
Restart the game (if it's been running).
Look over the portraits in game until you find your addition. If you've already created your character, just click on the portrait on the character screen.
This replaces one of the built in character portraits. But if you want custom portraits, that shouldn't be a problem.
The game will use a maximum of 15 images (head01 - head15).