Core War

Core War is a programming game where assembly-language programs battle in the memory of a virtual computer. I have participated in this game in an on-and-off fashion since 1996, writing tutorials, organizing tournaments and even occasionally playing the game itself (with little success). This page does not attempt to list all of the Core War -related material I've written (most of it can be found in the newsgroup, but should serve as an overview of sorts.

The beginners' guide to Redcode

I consider this guide my major contribution to Core War. Mostly written in 1997, it still remains one of the best starting points for people interested in learning the basics of the game. The guide also contains one of the few complete descriptions of the current de facto Redcode standard.

I've also written a number of shorter Core War -related tutorials and explanations, mostly as a result of questions asked on Some of those are listed below, in no particular order.

Ilmari's Mini-Tournaments 1 and 2

Over the years, I've organized two single-round Core War tournaments. The first, held in April-May 1998, attempted to create an Iterated Prisoners' Dilemma -like situation between P-switchers, in the hope that co-operative strategies would emerge. The results should speak for themselves...

The second mini-tournament was an ordinary round-robin melee, except that it was fought in a very small 80-instruction core, with a maximum warrior length of 4 instructions. The most surprising result in this tournament was the unexpected success of genetic algorithms over human coders, with the top two warriors both produced by a GA.

Published warriors

The following programs were my entries in Anton Marsden's somewhat unconventional Core War tournament of 1997, which I somehow managed to win! This was the first and the last time I ever ranked even in the top half of a tournament -- needless to say, I was just a little bit surprised.

Time Lag (1997, scan + cont. clear) is my self-splitting scanner, probably the first and only one of its kind. It works too, it just doesn't score too well because it's big and slow. As a proof-of-concept warrior, though, it's quite successful.

I also came up with the Vortex Launch (1999, imp), a compact way of launching heavy interleaved imp spirals using parallel processes, perfectly suited for silks. In fact, it turns out I'd reinvented an idea used much earlier by John K. Wilkinson in his famous Return Of The Jedimp, but the source for his warrior wasn't published until June 2000.

The Core War Imp Ring