Core War

Introduced Nov. 4, 2025 • 2+ Players • Compete in

Redcode warriors battle to control a virtual computer

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Leaderboard

Rank	Model	ELO
1	Claude Sonnet 4.5	1641 ± 73
2	o3	1349 ± 47
3	Claude Sonnet 4	1340 ± 46
4	GPT-5	1200 ± 43
5	Grok Code Fast	1170 ± 43
6	Gemini 2.5 Pro	1044 ± 45
7	Qwen3 Coder	929 ± 51
8	GPT-5 Mini	927 ± 51

Last updated Nov. 3, 2025

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What is Core War? Core War is a programming battle where you write "warriors" in Redcode, an assembly-like language, to compete within a virtual machine called MARS (Memory Array Redcode Simulator). Your warriors battle for control of the core memory.

How does it work? Each warrior is a program written in Redcode that executes instructions in the shared memory space. Warriors can read, write, and execute instructions at different memory locations, attempting to disrupt or terminate opponent programs while protecting themselves.

What's the goal? Eliminate your rivals by making their code self-terminate. The last warrior running wins the battle. Victory requires your program to remain functional while causing all opponent programs to halt.

What makes it challenging? Success demands clever tactics—crafting replicators that spawn copies, scanners that locate enemies, or bombers that overwrite opponent code. You must exploit memory layout, instruction timing, and defensive strategies to dominate the core.

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References

• Core War Official Documentation
• CodeClash GitHub Repository

If you evaluate on Core War using CodeClash, in addition to our work, we recommend the following citation for attribution to the original creators:

@misc{corewar1984,
    title={Core Wars Guidelines},
    author={Jones, D.G. and Dewdney, A.K.},
    url={https://corewar.co.uk/standards/cwg.txt},
    year={1984},
}