SpaceChem Bench: The Blue Danube

research_1 Hard Sensing Single-reactor Atropos Station Random inputs · SpaceChem Bench report →

Random inputs: α Hydrogen (H) / Hydrogen (H2). Output: ψ Hydrogen (H2) ×20. Features: Bonders (4), Sensor, Random inputs.

In SpaceChem Bench, 16 LLMs each had one attempt at this SpaceChem puzzle, with 60 minutes to build a working solution and keep optimizing it, without seeing the community archive. 16 of 16 models solved it. No model found a new Pareto-frontier point beyond the frozen community archive.

16 / 16models solved it
202best LLM cycles (154 community)
0new frontier points

Records

ScoreCommunity bestBest LLMModel
Cycles154202Opus 5.5 · +31%
Reactors11DeepSeek V4.1 Flash Ties record
Symbols1012Gemini 4 Argon · +20%

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
01Opus 5.5Yes202114—
02GPT-6 AstraYes203115—
03Fable 5.1Yes207116—
04GPT-6.1 SolYes218115—
05Gemini 4 ArgonYes219112—
06Haiku 5.5Yes227115—
07Sonnet 5.5Yes234114—
08Gemini 3.8 FlashYes260116—
09Grok 4.7Yes286121—
10GLM-5.3Yes294118—
11DeepSeek V4.1 FlashYes306115—
12Kimi K3.1 ProYes384115—
13Muse Spark 1.3Yes384116—
14GPT-6 LunaYes438119—
15Muse Wonder 1.0Yes611130—
16MiMo-V2.6-ProYes860125—

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.

Opus 5.5 Fewest cycles

202 cycles · 1 reactor · 25 symbolsresearch_1.202-1-25.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← IN α GRAB ?H→ DROP GRAB FLIP→ IN α DROP OUT ψ DROP B+ DROP

Running in the game

Opus 5.5 solution running on research_1 in SpaceChem
SpaceChem Community Edition export (research_1.202-1-25.txt)
SOLUTION:The Blue Danube,Player,0-0-0
COMPONENT:'drag-advanced-reactor',2,0,''
MEMBER:'instr-start',180,0,32,8,1,0,0
MEMBER:'instr-start',180,0,128,3,2,0,0
MEMBER:'feature-bonder',-1,0,1,0,1,0,0
MEMBER:'feature-bonder',-1,0,1,1,1,0,0
MEMBER:'feature-bonder',-1,0,1,9,6,0,0
MEMBER:'feature-bonder',-1,0,1,9,7,0,0
MEMBER:'feature-sensor',-1,0,1,3,1,0,0
MEMBER:'instr-arrow',180,0,64,3,2,0,0
MEMBER:'instr-input',-1,0,128,2,2,0,0
MEMBER:'instr-arrow',-90,0,64,1,2,0,0
MEMBER:'instr-grab',-1,1,128,1,1,0,0
MEMBER:'instr-arrow',0,0,64,1,1,0,0
MEMBER:'instr-sensor',0,0,128,2,1,0,1
MEMBER:'instr-arrow',-90,0,64,2,1,0,0
MEMBER:'instr-grab',-1,2,128,3,1,0,0
MEMBER:'instr-arrow',90,0,64,3,1,0,0
MEMBER:'instr-arrow',180,0,64,2,0,0,0
MEMBER:'instr-toggle',0,0,128,2,0,0,0
MEMBER:'instr-input',-1,0,128,1,0,0,0
MEMBER:'instr-arrow',90,0,64,0,0,0,0
MEMBER:'instr-grab',-1,2,128,0,1,0,0
MEMBER:'instr-arrow',0,0,64,0,1,0,0
MEMBER:'instr-arrow',90,0,64,4,0,0,0
MEMBER:'instr-arrow',180,0,64,4,3,0,0
MEMBER:'instr-arrow',-90,0,64,3,3,0,0
MEMBER:'instr-grab',-1,1,32,3,1,0,0
MEMBER:'instr-arrow',0,0,16,3,1,0,0
MEMBER:'instr-output',-1,0,32,4,1,0,0
MEMBER:'instr-bond',-1,0,32,5,1,0,0
MEMBER:'instr-grab',-1,2,32,6,1,0,0
MEMBER:'instr-arrow',180,0,16,6,1,0,0
MEMBER:'instr-grab',-1,2,128,4,1,0,0

GPT-6 Astra Fewest reactors

203 cycles · 1 reactor · 20 symbolsresearch_1.203-1-20.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→ ?H→ GRAB IN α FLIP← DROP DROP G/D B+ OUT ψ G/D

Running in the game

GPT-6 Astra solution running on research_1 in SpaceChem
SpaceChem Community Edition export (research_1.203-1-20.txt)
SOLUTION:The Blue Danube,Player,0-0-0
COMPONENT:'drag-advanced-reactor',2,0,''
MEMBER:'instr-start',-90,0,128,1,3,0,0
MEMBER:'instr-start',0,0,32,2,1,0,0
MEMBER:'feature-bonder',-1,0,1,2,0,0,0
MEMBER:'feature-bonder',-1,0,1,3,0,0,0
MEMBER:'feature-sensor',-1,0,1,3,1,0,0
MEMBER:'feature-bonder',-1,0,1,0,7,0,0
MEMBER:'feature-bonder',-1,0,1,9,7,0,0
MEMBER:'instr-arrow',90,0,64,1,0,0,0
MEMBER:'instr-arrow',0,0,64,1,1,0,0
MEMBER:'instr-arrow',-90,0,64,1,2,0,0
MEMBER:'instr-arrow',0,0,64,2,0,0,0
MEMBER:'instr-arrow',-90,0,64,2,1,0,0
MEMBER:'instr-arrow',90,0,64,3,0,0,0
MEMBER:'instr-arrow',90,0,64,3,1,0,0
MEMBER:'instr-arrow',180,0,64,3,2,0,0
MEMBER:'instr-grab',-1,1,128,1,1,0,0
MEMBER:'instr-input',-1,0,128,1,2,0,0
MEMBER:'instr-toggle',180,0,128,2,0,0,0
MEMBER:'instr-sensor',0,0,128,2,1,0,1
MEMBER:'instr-grab',-1,2,128,3,0,0,0
MEMBER:'instr-grab',-1,2,128,3,1,0,0
MEMBER:'instr-arrow',0,0,16,3,1,0,0
MEMBER:'instr-arrow',180,0,16,6,1,0,0
MEMBER:'instr-grab',-1,0,32,3,1,0,0
MEMBER:'instr-bond',-1,0,32,4,1,0,0
MEMBER:'instr-output',-1,0,32,5,1,0,0
MEMBER:'instr-grab',-1,0,32,6,1,0,0

Gemini 4 Argon Fewest symbols

461 cycles · 1 reactor · 12 symbolsresearch_1.461-1-12.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← ?H→ GRAB B+ G/D OUT ψ G/D DROP IN α

Running in the game

Gemini 4 Argon solution running on research_1 in SpaceChem
SpaceChem Community Edition export (research_1.461-1-12.txt)
SOLUTION:The Blue Danube,Player,0-0-0
COMPONENT:'drag-advanced-reactor',2,0,''
MEMBER:'instr-start',-90,0,128,8,2,0,0
MEMBER:'instr-start',180,0,32,4,6,0,0
MEMBER:'feature-bonder',-1,0,1,4,2,0,0
MEMBER:'feature-bonder',-1,0,1,5,2,0,0
MEMBER:'feature-sensor',-1,0,1,1,1,0,0
MEMBER:'feature-bonder',-1,0,1,0,7,0,0
MEMBER:'feature-bonder',-1,0,1,9,7,0,0
MEMBER:'instr-arrow',90,0,64,0,1,0,0
MEMBER:'instr-arrow',0,0,64,0,2,0,0
MEMBER:'instr-arrow',180,0,64,8,1,0,0
MEMBER:'instr-arrow',-90,0,64,8,2,0,0
MEMBER:'instr-sensor',0,0,128,0,1,0,1
MEMBER:'instr-grab',-1,1,128,1,1,0,0
MEMBER:'instr-bond',-1,0,128,4,2,0,0
MEMBER:'instr-grab',-1,0,128,5,2,0,0
MEMBER:'instr-output',-1,0,128,6,1,0,0
MEMBER:'instr-grab',-1,0,128,6,2,0,0
MEMBER:'instr-grab',-1,2,128,7,1,0,0
MEMBER:'instr-input',-1,0,128,8,1,0,0