SpaceChem Bench: A Brief History of SpaceChem

research_tutorial_2 Easy Bonding & routing Single-reactor Sernimir II · SpaceChem Bench report →

Inputs: α Hydrogen (H), β Chlorine (Cl). Output: ω Hydrochloric Acid (HCl) ×10. Features: Bonders (4).

In SpaceChem Bench, 16 LLMs each had one attempt at this SpaceChem puzzle, with 10 minutes to build a working solution and keep optimizing it, without seeing the community archive. 13 of 16 models solved it. No model found a new Pareto-frontier point beyond the frozen community archive.

13 / 16models solved it
75best LLM cycles (75 community)
0new frontier points

Records

ScoreCommunity bestBest LLMModel
Cycles7575Gemini 4 Argon Ties record
Reactors11DeepSeek V4.1 Flash Ties record
Symbols1010Fable 5.1 Ties record

Community records from the community archive when we froze it on October 18, 2026. A point counts only after fresh-game replay and SChem’s precognition check.

Pareto frontier

Pareto explorer

Lower is better ↙
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Community archiveModel frontier pointNew frontier point
Select a point with the mouse or keyboard to inspect its scores and reactor blueprint.

Search over time

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Every model

ModelSolvedBest cyclesBest reactorsBest symbolsNew frontier points
01Gemini 4 ArgonYes75110—
02GPT-6 AstraYes76110—
03Fable 5.1Yes77110—
04Opus 5.5Yes78110—
05GPT-6.1 SolYes82110—
06Gemini 3.8 FlashYes84110—
07Sonnet 5.5Yes103112—
08Muse Wonder 1.0Yes104114—
09Grok 4.7Yes107114—
10Haiku 5.5Yes120117—
11Muse Spark 1.3Yes175116—
12Kimi K3.1 ProYes209120—
13DeepSeek V4.1 FlashYes210120—
14GLM-5.3No————
15GPT-6 LunaNo————
16MiMo-V2.6-ProNo————

Best scores can come from different solutions. New frontier points are not matched or beaten on all three scores by any community solution.

Best model solutions

These solutions are in SpaceChem Community Edition export format and released under the MIT License. All of this puzzle’s model solutions are on GitHub and Hugging Face.

Gemini 4 Argon Fewest cyclesFewest reactors

75 cycles · 1 reactor · 20 symbolsresearch_tutorial_2.75-1-20.txt on GitHub

Layout

α β ψ ω 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 ↓ → ← ↑ ↓ → ← ↑ S← S← G/D G/D IN β IN α B+ B+ IN α OUT ω G/D G/D IN β OUT ω

Running in the game

Gemini 4 Argon solution running on research_tutorial_2 in SpaceChem
SpaceChem Community Edition export (research_tutorial_2.75-1-20.txt)
SOLUTION:A Brief History of SpaceChem,Player,0-0-0
COMPONENT:'drag-starter-reactor',2,0,''
MEMBER:'instr-start',180,0,128,4,1,0,0
MEMBER:'instr-start',180,0,32,2,1,0,0
MEMBER:'feature-bonder',-1,0,1,1,4,0,0
MEMBER:'feature-bonder',-1,0,1,1,5,0,0
MEMBER:'feature-bonder',-1,0,1,0,7,0,0
MEMBER:'feature-bonder',-1,0,1,9,7,0,0
MEMBER:'instr-arrow',90,0,64,1,1,0,0
MEMBER:'instr-arrow',0,0,64,1,4,0,0
MEMBER:'instr-arrow',180,0,64,6,1,0,0
MEMBER:'instr-arrow',-90,0,64,6,4,0,0
MEMBER:'instr-grab',-1,0,128,1,1,0,0
MEMBER:'instr-input',-1,1,128,1,2,0,0
MEMBER:'instr-bond',-1,0,128,1,4,0,0
MEMBER:'instr-input',-1,0,128,3,1,0,0
MEMBER:'instr-output',-1,1,128,5,4,0,0
MEMBER:'instr-grab',-1,0,128,6,4,0,0
MEMBER:'instr-arrow',90,0,16,1,1,0,0
MEMBER:'instr-arrow',0,0,16,1,4,0,0
MEMBER:'instr-arrow',180,0,16,6,1,0,0
MEMBER:'instr-arrow',-90,0,16,6,4,0,0
MEMBER:'instr-grab',-1,0,32,1,1,0,0
MEMBER:'instr-input',-1,0,32,1,2,0,0
MEMBER:'instr-bond',-1,0,32,1,4,0,0
MEMBER:'instr-input',-1,1,32,2,4,0,0
MEMBER:'instr-output',-1,1,32,6,2,0,0
MEMBER:'instr-grab',-1,0,32,6,4,0,0

GPT-6 Astra Fewest symbols

154 cycles · 1 reactor · 10 symbolsresearch_tutorial_2.154-1-10.txt on GitHub

Layout

α β ψ ω 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 ↓ → ← ↑ S← S← GRAB IN β B+ IN α DROP OUT ω

Running in the game

GPT-6 Astra solution running on research_tutorial_2 in SpaceChem
SpaceChem Community Edition export (research_tutorial_2.154-1-10.txt)
SOLUTION:A Brief History of SpaceChem,Player,0-0-0
COMPONENT:'drag-starter-reactor',2,0,''
MEMBER:'instr-start',180,0,128,3,1,0,0
MEMBER:'instr-start',180,0,32,1,0,0,0
MEMBER:'feature-bonder',-1,0,1,1,4,0,0
MEMBER:'feature-bonder',-1,0,1,1,5,0,0
MEMBER:'feature-bonder',-1,0,1,0,7,0,0
MEMBER:'feature-bonder',-1,0,1,9,7,0,0
MEMBER:'instr-arrow',90,0,64,1,1,0,0
MEMBER:'instr-arrow',0,0,64,1,4,0,0
MEMBER:'instr-arrow',180,0,64,6,1,0,0
MEMBER:'instr-arrow',-90,0,64,6,4,0,0
MEMBER:'instr-grab',-1,1,128,1,1,0,0
MEMBER:'instr-input',-1,1,128,1,2,0,0
MEMBER:'instr-bond',-1,0,128,1,4,0,0
MEMBER:'instr-input',-1,0,128,2,1,0,0
MEMBER:'instr-grab',-1,2,128,6,4,0,0
MEMBER:'instr-output',-1,1,32,0,0,0,0