DM2TIM
Core War · Credits
2026-07-18 · 4 min read

Attribution

AI notice: This text is created with the support of AI systems; it is reviewed editorially and taken responsibility for before publication.

Almost nothing on these pages was invented by us. Core War is a forty-year collective work, and this reference mostly explains other people's.

This page names them. Not out of politeness — in this scene, attribution is the precondition for anybody publishing anything at all.

The game

A. K. Dewdney introduced Core War in his Computer Recreations column in Scientific American in 1984 and developed it further over the following years. The two programs practically everyone starts with are also his: the imp and the dwarf. Both appear in the learning path here.

The ICWS (International Core Wars Society) published the standards still played on today — ICWS'88 and the never formally ratified but de facto authoritative '94 draft.

Chip Wendell wrote Mice, winner of the 1986 ICWS tournament and the archetype of the replicator. The idea of reproducing instead of attacking shapes the game to this day.

The tools

pMARS, the reference simulator, is by Albert Ma, Nándor Sieben, Stefan Strack and Mintardjo Wangsaw. It is maintained today by John Metcalf. Our own engine is a rebuild of pMARS and measures itself against its behaviour — in case of doubt, pMARS is right.

The number tools, without which nobody would find sensible constants: Optima by Nándor Sieben, Corestep and Makeimp by Jay Han, Mopt and MTS by Stefan Strack.

The optimisers: Optimax by Sasha Zapf and Christian Schmidt, the Simulated Annealing Optimizer by John Metcalf, Randy by inversed.

The benchmark tools: koth by Philip Kendall, TestWarrior and Corewar Tournament by Phil Knight.

The hills

Christoph C. Birk runs the Koenigstuhl — the unlimited hill holding over 1100 warriors from three decades, where every entry stays forever.

Practically every number on these pages comes from that field: the class matrix, the field statistics, the style tagging, the rounds study. Without a place where today's programs can measure themselves against three decades of warrior craft — open, maintained and publicly readable — this reference would not exist. Particular thanks for that.

KOTH.org has been running since the early nineties and is the oldest continuously operated hill server in the scene. KOTH@SAL runs the smaller rule sets, including the beginner hill we recommend to newcomers.

John Metcalf maintains corewar.co.uk — tutorials, strategy articles, a simulator collection, FAQ, tournament archives and the Hall of Fame. The tool and hill overviews in this reference are based on his compilations.

The warriors we learned from

Our own programs stand on other people's shoulders, and very concretely so:

Azathoth by John Metcalf — a paper/stone with a quickscanner whose decode structure we followed instruction by instruction. The decisive trick lies in a multiplicative number lattice where a single multiplication reconstructs the location of a find. Our Arvon builds on it — and subsequently displaced Azathoth from rank 1, which gave us mixed feelings.

King Cobra and Eternal Exile by inversed — the oneshot lineage our Kaitain stands on, and the fixed-length-wipe scanner from which our clrsrc emerged.

Beyond that, the many authors whose warriors populate the Koenigstuhl field and whose results went into our measurements — among them Roy van Rijn, Steve Gunnell, Christian Schmidt, Ken Espiritu, Andrzej Maciejczak and many more.

What we ship and what we do not

A Redcode warrior is a copyrighted program. Being publicly readable on a hill is not a licence. We therefore hold to a clear line:

Shipped are only the historic classics that have appeared in published articles since the eighties and are effectively common property of the scene — imp, dwarf, mice — plus warriors we wrote ourselves. The latter are freely usable.

Not shipped is foreign code. Where we explain foreign warriors we describe them and link the original source. Short excerpts in running text, with author and origin, stand as quotation within an explanatory context.

The ten teaching examples on these pages are therefore mostly our own builds. That is legally clean and didactically better besides: they are written for readability rather than strength, and they build on one another.

And our own submissions

Every warrior we have submitted carries, in its ;strategy line, a note of what it builds on. That is the custom of the scene and we think it is right: it costs nothing, it is honest, and it makes visible how an idea develops over years.

If you find a missing or incorrect attribution on these pages, please tell us — contact via the imprint. We will correct it gladly and quickly.

← Core War overview