DM2TIM
Reference
2026-07-19 · 5 min read

Hills and community

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

Core War has no company behind it and no product cycle. What it has is a small scene that has been running the same servers and discussing the same questions for over thirty years. This page shows where to find both.

How to submit is in the learning path under Onto a hill. This page is about where.

The active hill servers

KOTH.org

The longest continuously operated Core War site. The classic displacement hill: fixed size, whoever is last drops off.

  • Address: koth.org
  • Hills: 94nop, 94 draft, multi-warrior, 88, 94x, icws, 94xm
  • Submission: email to koth@koth.org, first line ;redcode-<hill>

The 94nop hill there is the scene's most important reference point and the basis for the Hall of Fame.

Status 19 July 2026: koth.org is running again. After a server migration and three weeks without a single computed battle, the hill resumed operation on 19 July at 18:24 UTC. Submissions are accepted, compiled and scored.

Two things to keep in mind. The site is currently reachable over http:// only — the server refuses encrypted connections. And the mail server sometimes takes minutes to respond. That is not a fault at your end: if you submit and get no immediate reply, wait rather than send again. A properly configured mail server keeps the message queued for days and delivers it automatically.

Koenigstuhl

The "infinite" hill run by Christoph C. Birk. Nobody drops off here — every submitted warrior stays in the field forever. Over the years it has grown into an archive of more than 1100 warriors spanning three decades.

The Koenigstuhl measures something different from a displacement hill: not whether you beat the current top, but how you hold up against the entire historical spectrum. It also publishes the source of every warrior — making it the best place to learn how other people solved problems.

Every figure and measurement in this reference comes from that field.

KOTH@SAL

Operated by the Survival Analysis Lab. This is where the smaller rule sets live, in which entirely different strategies work.

The beginner hill is the best first address. Small field, fewer top warriors, and a result that does not immediately discourage. If you have worked through the learning path, start there — not on 94nop.

The small rule sets are also worthwhile in themselves: on a nano hill with a tiny core and few permitted instructions, a good idea can achieve more than years of fine-tuning.

Further hills

Newton's Hills (newton.freehostia.com/hills) runs hills specifically for evolved warriors — "94 evolved", "tiny evolved" and "94 mixed".

corewar.co.uk runs two unlimited hills for the tiny and nano rule sets.

The Hall of Fame

corewar.co.uk maintains a Hall of Fame. You cannot apply — admission follows a purely mechanical criterion.

What counts is a warrior's age: how many other people's submissions it has survived on a displacement hill without being pushed off. On the 94nop hill the threshold is 100; for the all-time list, 1000.

That is a remarkably good criterion, because it does not measure form on the day but durability. A warrior that reaches rank 1 narrowly and is then taken apart by the next three submissions never gets in. One that sits at rank 8 for years and outlasts everything does.

It takes time accordingly. On a quiet hill, a hundred foreign submissions can mean months to years.

Where the scene meets

rec.games.corewar is the newsgroup where discussion has taken place since 1991. It remains the place where new warriors are announced, techniques explained and tournaments called. Reachable via Google Groups or a Usenet provider; the archives go back thirty years and are a resource in their own right.

COREWAR-L is a mailing list hosted by KOTH.org that mirrors the newsgroup — handy if you would rather not set up Usenet access.

#COREWARS on Libera Chat is the scene's IRC channel, there since 2021. There is also a Discord channel and an X account (@xcorewar).

corewar.co.uk is the unofficial centre: tutorials, strategy articles, a simulator collection, FAQ, glossary, tournament archives and the Hall of Fame. If you want to read further after this reference, that is the next address.

Etiquette

The scene is small, friendly and long-lived. A few things that count for more here than elsewhere:

Credit your sources. Almost every modern warrior builds on somebody. If you have taken a scan structure or developed a published idea further, put it in the ;strategy line. That is not a concession here but basic decency — and it costs nothing, because everyone can see where things come from anyway.

Do not submit by the minute. Every submission is computed against the entire field. Uploading ten variants in a row is impolite — and unnecessary, since you can measure that locally, faster and with more rounds.

Ask. The newsgroup has been answering beginners' questions patiently for thirty years. This is not a scene where you have to prove yourself first.

A word on the state of things

Core War is a niche game, and it shows. Servers go down, pages disappear, some address in an older tutorial leads nowhere. The koth.org migration, with its days-long outage, is an example.

At the same time the game has been running since 1984 and the newsgroup since 1991. What is here has outlasted three decades — more than can be said for most of the online services that have come and gone since.

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