Monster Mechanics

Monster Mechanics is a computer game where the player has to build a creature out of body parts. The creature has to fight other creatures to acquire mutagen, a resource needed for growing new body parts.


Screenshot of Monster Mechanics, showing a four-legged player-built (blue) creature firing thistle projectiles at an enemy (red) creature
Screenshot of Monster Mechanics, showing a one-legged player-built (blue) creature fighting an enemy (red) creature in close combat
Screenshot of Monster Mechanics, showing a many-winged player-built (blue) creature ramming an enemy (red) creature


Monster Mechanics was created by Daniel Pope and Andrew Kelley for the Python game programming contest Pyweek in September 2011, which had the motto Mutate!. The game is free software, licensed under the GPLv3.


Monster Mechanics depends on Pygame, Pyglet and the Python bindings for the physics engine Box2D. The dependencies are available in Debian; they can be installed using apt-get install python-pygame python-pyglet python-box2d.


  • Hearts heal attached body parts, but not themselves.
  • Body parts attached to lungs have improved performance.
  • Thistle guns have recoil and can make a monster fall over.
  • Mutagen bladders raise the maximum limit of mutagen storage.
  • If a creature has legs, it can be controlled using the arrow keys.
  • Images and JSON data for created monsters lie in the data/saves folder.


Monster Mechanics crashes on some keyboard input, like the German character “Capital sharp s” () and the X11 keys XF86Back and XF86Forward (“back” and “forward” in browser history).