# Achilles

### What is Achilles?

Achilles is an evolution simulation based on Larry Yaeger's PolyWorld. It uses Hebbian neural networks, and an extremely simplified physical model that allows virtual organisms to interact freely in a simulated environment.

### Where can I get it?

- Github tags
- Debian package page

### What platforms does this work for?

Achilles was designed and compiled originally on Linux, but it is completely composed of portable C++ code and uses only portable libs such as SDL and OpenGL, therefore it should be trivial to port. All that is needed is hardware to compile on. Any porting efforts that are in progress or successful are welcome to contribute patches back to the main source tree.

### What do I need?

You need an implementation of OpenGL, currently its been tested only with Mesa3D the "unofficial" implementation of OpenGL. You need GLU and GLUT which are included with Mesa, and should be with most other OpenGL implementations. You need Simple Directmedia Layer , a crossplatform library for 2D graphics that works with GLUT to arrange windowing-system related things for Mesa.

### More information

Achilles is licensed under the GNU's General Protection License, therefore it is free to redistribute so long as the license is kept intact and basically you give credit where credit is due. Read the license for more information.

If you wish to submit any questions, comments, bug reports, patches, source code, ports to other platforms, etc... feel free to email.

### What do the colors mean?

- The organism colors:
  - The brighter red, the more aggressive
  - The brighter blue, the more likely to mate
  - Yellow indicates `dead' organisms, or sources of food
- The spikes that flash between the organisms:
  - Red means attack
  - Blue means mate
  - Yellow means feeding

The organisms are given the color of surrounding organisms as an input to the neural network. This emulates ``vision''.

### Does size matter?

Size is an attribute of the genetic algorithms and thus each organism obtains its dimensions from its parents. Otherwise, not particularly.

### Screenshots

1 2 3 4 5

### Credits

Copyright 2000-2026: Matthew Danish (mrd at debian dot org)

Thanks go out to these contributors over the years: Christoph Berg, Matej Vela, Michael Ablassmeier, Manfred Lichtenstern, Mohammed Adnène Trojette, Gianfranco Costamagna, Tobias Frost, David William Richmond Davies-Jones, Joao Eriberto Mota Filho, Alexandre Detiste. They helped pick up the project when I didn't have time to maintain it.

Updated: 10 Feb 2026. This website is a modified copy of the original Sourceforge website (which is still operational but unmaintained for 25+ years).