SpaceChem Bench: The Plot Thickens

mining_7 Medium Sensing Single-reactor Hephaestus IV · SpaceChem Bench report →

Inputs: α Carbon (C), β Hydrogen (H). Output: ψ Polyethylene ((C2H4)n) ×10. Features: Bonders (4), Sensor, Large output (4×8).

In SpaceChem Bench, 16 LLMs each had one attempt at this SpaceChem puzzle, with 40 minutes to build a working solution and keep optimizing it, without seeing the community archive. 9 of 16 models solved it. Together they found 3 new Pareto-frontier points beyond the frozen community archive.

9 / 16models solved it
468best LLM cycles (419 community)
3new frontier points

Records

ScoreCommunity bestBest LLMModel
Cycles419468GPT-6.1 Sol · +12%
Reactors11Fable 5.1 Ties record
Symbols1415GPT-6.1 Sol · +7%

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
01GPT-6.1 SolYes4681152
02Gemini 4 ArgonYes7061151
03GPT-6 AstraYes567120—
04Opus 5.5Yes765119—
05Sonnet 5.5Yes849130—
06Fable 5.1Yes889135—
07Muse Wonder 1.0Yes2,091136—
08Kimi K3.1 ProYes2,155133—
09Gemini 3.8 FlashYes2,871136—
10DeepSeek V4.1 FlashNo————
11GLM-5.3No————
12GPT-6 LunaNo————
13Grok 4.7No————
14Haiku 5.5No————
15MiMo-V2.6-ProNo————
16Muse Spark 1.3No————

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.

GPT-6.1 Sol Fewest cycles★ New frontier point

468 cycles · 1 reactor · 31 symbolsmining_7.468-1-31.txt on GitHub

Layout

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

Running in the game

GPT-6.1 Sol solution running on mining_7 in SpaceChem
SpaceChem Community Edition export (mining_7.468-1-31.txt)
SOLUTION:The Plot Thickens,Player,0-0-0
COMPONENT:'drag-largeoutput-reactor',2,0,''
MEMBER:'instr-start',0,0,128,0,0,0,0
MEMBER:'instr-start',180,0,32,4,6,0,0
MEMBER:'feature-bonder',-1,0,1,1,4,0,0
MEMBER:'feature-bonder',-1,0,1,2,4,0,0
MEMBER:'feature-bonder',-1,0,1,1,5,0,0
MEMBER:'feature-bonder',-1,0,1,1,6,0,0
MEMBER:'feature-sensor',-1,0,1,7,6,0,0
MEMBER:'instr-arrow',90,0,64,1,0,0,0
MEMBER:'instr-arrow',90,0,64,1,1,0,0
MEMBER:'instr-arrow',0,0,64,1,6,0,0
MEMBER:'instr-arrow',180,0,64,2,1,0,0
MEMBER:'instr-arrow',-90,0,64,2,6,0,0
MEMBER:'instr-input',-1,0,128,1,0,0,0
MEMBER:'instr-grab',-1,1,128,1,1,0,0
MEMBER:'instr-sync',-1,0,128,1,2,0,0
MEMBER:'instr-input',-1,1,128,1,3,0,0
MEMBER:'instr-input',-1,1,128,1,6,0,0
MEMBER:'instr-input',-1,1,128,2,1,0,0
MEMBER:'instr-input',-1,0,128,2,2,0,0
MEMBER:'instr-bond',-1,0,128,2,3,0,0
MEMBER:'instr-grab',-1,2,128,2,4,0,0
MEMBER:'instr-arrow',90,0,16,1,1,0,0
MEMBER:'instr-arrow',0,0,16,1,6,0,0
MEMBER:'instr-arrow',180,0,16,2,1,0,0
MEMBER:'instr-arrow',-90,0,16,2,6,0,0
MEMBER:'instr-arrow',180,0,16,7,6,0,0
MEMBER:'instr-grab',-1,1,32,1,1,0,0
MEMBER:'instr-input',-1,1,32,1,3,0,0
MEMBER:'instr-bond',-1,0,32,1,6,0,0
MEMBER:'instr-bond',-1,0,32,2,1,0,0
MEMBER:'instr-input',-1,0,32,2,2,0,0
MEMBER:'instr-bond',-1,0,32,2,3,0,0
MEMBER:'instr-grab',-1,2,32,2,4,0,0
MEMBER:'instr-sync',-1,0,32,2,5,0,0
MEMBER:'instr-sensor',0,0,32,2,6,0,6
MEMBER:'instr-rotate',-1,1,32,3,6,0,0
MEMBER:'instr-output',-1,0,32,6,6,0,0
MEMBER:'instr-grab',-1,2,32,7,6,0,0

GPT-6.1 Sol Fewest reactors★ New frontier point

469 cycles · 1 reactor · 29 symbolsmining_7.469-1-29.txt on GitHub

Layout

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

Running in the game

GPT-6.1 Sol solution running on mining_7 in SpaceChem
SpaceChem Community Edition export (mining_7.469-1-29.txt)
SOLUTION:The Plot Thickens,Player,0-0-0
COMPONENT:'drag-largeoutput-reactor',2,0,''
MEMBER:'instr-start',-90,0,128,2,7,0,0
MEMBER:'instr-start',-90,0,32,2,3,0,0
MEMBER:'feature-bonder',-1,0,1,1,4,0,0
MEMBER:'feature-bonder',-1,0,1,2,4,0,0
MEMBER:'feature-bonder',-1,0,1,1,5,0,0
MEMBER:'feature-bonder',-1,0,1,1,6,0,0
MEMBER:'feature-sensor',-1,0,1,7,6,0,0
MEMBER:'instr-arrow',90,0,64,1,1,0,0
MEMBER:'instr-arrow',0,0,64,1,6,0,0
MEMBER:'instr-arrow',180,0,64,2,1,0,0
MEMBER:'instr-arrow',-90,0,64,2,6,0,0
MEMBER:'instr-arrow',180,0,64,7,6,0,0
MEMBER:'instr-grab',-1,1,128,1,1,0,0
MEMBER:'instr-input',-1,1,128,1,3,0,0
MEMBER:'instr-bond',-1,0,128,1,4,0,0
MEMBER:'instr-input',-1,1,128,1,6,0,0
MEMBER:'instr-input',-1,1,128,2,1,0,0
MEMBER:'instr-input',-1,0,128,2,2,0,0
MEMBER:'instr-grab',-1,2,128,2,4,0,0
MEMBER:'instr-sync',-1,0,128,2,5,0,0
MEMBER:'instr-sensor',0,0,128,2,6,0,6
MEMBER:'instr-rotate',-1,1,128,3,6,0,0
MEMBER:'instr-output',-1,0,128,6,6,0,0
MEMBER:'instr-grab',-1,2,128,7,6,0,0
MEMBER:'instr-arrow',90,0,16,1,1,0,0
MEMBER:'instr-arrow',0,0,16,1,6,0,0
MEMBER:'instr-arrow',180,0,16,2,1,0,0
MEMBER:'instr-arrow',-90,0,16,2,6,0,0
MEMBER:'instr-grab',-1,1,32,1,1,0,0
MEMBER:'instr-sync',-1,0,32,1,2,0,0
MEMBER:'instr-input',-1,1,32,1,3,0,0
MEMBER:'instr-bond',-1,0,32,1,4,0,0
MEMBER:'instr-bond',-1,0,32,1,6,0,0
MEMBER:'instr-bond',-1,0,32,2,1,0,0
MEMBER:'instr-input',-1,0,32,2,2,0,0
MEMBER:'instr-grab',-1,2,32,2,4,0,0

GPT-6.1 Sol Fewest symbols

822 cycles · 1 reactor · 15 symbolsmining_7.822-1-15.txt on GitHub

Layout

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

Running in the game

GPT-6.1 Sol solution running on mining_7 in SpaceChem
SpaceChem Community Edition export (mining_7.822-1-15.txt)
SOLUTION:The Plot Thickens,Player,0-0-0
COMPONENT:'drag-largeoutput-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',-1,0,1,2,4,0,0
MEMBER:'feature-bonder',-1,0,1,1,5,0,0
MEMBER:'feature-bonder',-1,0,1,1,6,0,0
MEMBER:'feature-sensor',-1,0,1,7,6,0,0
MEMBER:'instr-arrow',90,0,64,1,1,0,0
MEMBER:'instr-arrow',0,0,64,1,6,0,0
MEMBER:'instr-arrow',180,0,64,2,1,0,0
MEMBER:'instr-arrow',-90,0,64,2,6,0,0
MEMBER:'instr-arrow',180,0,64,7,6,0,0
MEMBER:'instr-grab',-1,1,128,1,1,0,0
MEMBER:'instr-input',-1,1,128,1,4,0,0
MEMBER:'instr-input',-1,1,128,1,6,0,0
MEMBER:'instr-input',-1,0,128,2,1,0,0
MEMBER:'instr-grab',-1,2,128,2,4,0,0
MEMBER:'instr-sensor',0,0,128,2,6,0,6
MEMBER:'instr-rotate',-1,1,128,3,6,0,0
MEMBER:'instr-output',-1,0,128,6,6,0,0
MEMBER:'instr-grab',-1,2,128,7,6,0,0
MEMBER:'instr-bond',-1,0,32,0,0,0,0