SpaceChem Bench: Challenge: Applied Fusion
fusion_6 Medium Multi-reactor production Multi-reactor Sikutar · 
SpaceChem Bench report →
Inputs: α Water (H2O). Output: ψ Phosphoric Acid (H3PO4) ×10. Features: Max reactors: 6, Fusion reactor.
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. 2 of 16 models solved it. No model found a new Pareto-frontier point beyond the frozen community archive.
2 / 16models solved it
4,879best LLM cycles (2,019 community)
0new frontier points
Records
| Score | Community best | Best LLM | Model |
|---|---|---|---|
| Cycles | 2,019 | 4,879 | GPT-6 Astra · +142% |
| Reactors | 1 | 3 | GPT-6 Astra · +200% |
| Symbols | 27 | 115 | GPT-6 Astra · +326% |
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
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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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The search over time
Best in-game score so far, before replay. Each score can come from a different solution, and lines stop when the episode ends.
Every model
| Model | Solved | Best cycles | Best reactors | Best symbols | New frontier points |
|---|---|---|---|---|---|
| 01GPT-6 Astra | Yes | 4,879 | 3 | 115 | — |
| 02GPT-6.1 Sol | Yes | 5,754 | 6 | 233 | — |
| 03DeepSeek V4.1 Flash | No | — | — | — | — |
| 04Fable 5.1 | No | — | — | — | — |
| 05GLM-5.3 | No | — | — | — | — |
| 06GPT-6 Luna | No | — | — | — | — |
| 07Gemini 3.8 Flash | No | — | — | — | — |
| 08Gemini 4 Argon | No | — | — | — | — |
| 09Grok 4.7 | No | — | — | — | — |
| 10Haiku 5.5 | No | — | — | — | — |
| 11Kimi K3.1 Pro | No | — | — | — | — |
| 12MiMo-V2.6-Pro | No | — | — | — | — |
| 13Muse Spark 1.3 | No | — | — | — | — |
| 14Muse Wonder 1.0 | No | — | — | — | — |
| 15Opus 5.5 | No | — | — | — | — |
| 16Sonnet 5.5 | No | — | — | — | — |
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 Astra
4,879 cycles · 3 reactors · 115 symbolsfusion_6.4879-3-115.txt on GitHub
Layout (Reactor 1 of 3)
Running in the game
SpaceChem Community Edition export (fusion_6.4879-3-115.txt)
SOLUTION:Challenge: Applied Fusion,Player,0-0-0
COMPONENT:'drag-fusion-reactor',10,10,''
MEMBER:'instr-start',0,0,128,0,2,0,0
MEMBER:'instr-start',-90,0,32,0,2,0,0
MEMBER:'feature-fuser',-1,0,1,4,4,0,0
MEMBER:'feature-bonder',-1,0,1,0,7,0,0
MEMBER:'feature-bonder',-1,0,1,9,7,0,0
MEMBER:'feature-bonder',-1,0,1,4,7,0,0
MEMBER:'feature-bonder',-1,0,1,6,7,0,0
MEMBER:'instr-arrow',90,0,64,0,0,0,0
MEMBER:'instr-arrow',0,0,64,0,2,0,0
MEMBER:'instr-arrow',90,0,64,2,2,0,0
MEMBER:'instr-arrow',0,0,64,2,5,0,0
MEMBER:'instr-arrow',0,0,64,4,4,0,0
MEMBER:'instr-arrow',-90,0,64,4,6,0,0
MEMBER:'instr-arrow',90,0,64,5,5,0,0
MEMBER:'instr-arrow',180,0,64,5,6,0,0
MEMBER:'instr-arrow',90,0,64,7,4,0,0
MEMBER:'instr-arrow',0,0,64,7,6,0,0
MEMBER:'instr-arrow',180,0,64,9,0,0,0
MEMBER:'instr-arrow',-90,0,64,9,6,0,0
MEMBER:'instr-input',-1,0,128,1,2,0,0
MEMBER:'instr-grab',-1,1,128,2,2,0,0
MEMBER:'instr-fuse',-1,0,128,4,4,0,0
MEMBER:'instr-grab',-1,1,128,5,4,0,0
MEMBER:'instr-fuse',-1,0,128,5,5,0,0
MEMBER:'instr-rotate',-1,0,128,5,6,0,0
MEMBER:'instr-grab',-1,2,128,7,4,0,0
MEMBER:'instr-output',-1,1,128,7,5,0,0
MEMBER:'instr-sync',-1,0,128,8,6,0,0
MEMBER:'instr-sync',-1,0,128,9,1,0,0
MEMBER:'instr-sync',-1,0,128,9,3,0,0
MEMBER:'instr-sync',-1,0,128,9,5,0,0
MEMBER:'instr-arrow',0,0,16,0,1,0,0
MEMBER:'instr-arrow',-90,0,16,0,2,0,0
MEMBER:'instr-arrow',90,0,16,7,1,0,0
MEMBER:'instr-arrow',180,0,16,7,2,0,0
MEMBER:'instr-sync',-1,0,32,0,1,0,0
MEMBER:'instr-input',-1,0,32,1,1,0,0
MEMBER:'instr-grab',-1,1,32,2,1,0,0
MEMBER:'instr-grab',-1,2,32,7,1,0,0
MEMBER:'instr-output',-1,0,32,7,2,0,0
PIPE:0,4,1
PIPE:0,5,1
PIPE:1,4,2
PIPE:1,5,2
COMPONENT:'drag-oceanic-input',4,11,''
PIPE:0,2,0
PIPE:0,3,0
PIPE:0,4,0
PIPE:0,5,0
COMPONENT:'drag-fusion-reactor',16,10,''
MEMBER:'instr-start',-90,0,128,0,5,0,0
MEMBER:'instr-start',-90,0,32,6,1,0,0
MEMBER:'feature-bonder',-1,0,1,5,3,0,0
MEMBER:'feature-bonder',-1,0,1,6,3,0,0
MEMBER:'feature-fuser',-1,0,1,4,4,0,0
MEMBER:'feature-bonder',-1,0,1,0,7,0,0
MEMBER:'feature-bonder',-1,0,1,9,7,0,0
MEMBER:'instr-arrow',0,0,64,0,4,0,0
MEMBER:'instr-arrow',-90,0,64,0,5,0,0
MEMBER:'instr-arrow',90,0,64,4,2,0,0
MEMBER:'instr-arrow',0,0,64,4,3,0,0
MEMBER:'instr-arrow',0,0,64,5,1,0,0
MEMBER:'instr-arrow',-90,0,64,5,6,0,0
MEMBER:'instr-arrow',90,0,64,6,3,0,0
MEMBER:'instr-arrow',180,0,64,6,6,0,0
MEMBER:'instr-arrow',90,0,64,7,0,0,0
MEMBER:'instr-arrow',180,0,64,7,2,0,0
MEMBER:'instr-arrow',90,0,64,8,1,0,0
MEMBER:'instr-arrow',180,0,64,8,5,0,0
MEMBER:'instr-arrow',180,0,64,9,0,0,0
MEMBER:'instr-arrow',-90,0,64,9,4,0,0
MEMBER:'instr-input',-1,1,128,0,4,0,0
MEMBER:'instr-grab',-1,1,128,1,4,0,0
MEMBER:'instr-fuse',-1,0,128,4,3,0,0
MEMBER:'instr-bond',-1,0,128,5,3,0,0
MEMBER:'instr-grab',-1,0,128,5,4,0,0
MEMBER:'instr-grab',-1,2,128,6,3,0,0
MEMBER:'instr-sync',-1,0,128,7,0,0,0
MEMBER:'instr-grab',-1,1,128,7,1,0,0
MEMBER:'instr-rotate',-1,1,128,7,2,0,0
MEMBER:'instr-sync',-1,0,128,7,4,0,0
MEMBER:'instr-sync',-1,0,128,8,0,0,0
MEMBER:'instr-grab',-1,2,128,8,4,0,0
MEMBER:'instr-output',-1,1,128,8,5,0,0
MEMBER:'instr-sync',-1,0,128,9,0,0,0
MEMBER:'instr-sync',-1,0,128,9,1,0,0
MEMBER:'instr-sync',-1,0,128,9,2,0,0
MEMBER:'instr-sync',-1,0,128,9,3,0,0
MEMBER:'instr-sync',-1,0,128,9,4,0,0
MEMBER:'instr-arrow',90,0,16,0,0,0,0
MEMBER:'instr-arrow',0,0,16,0,1,0,0
MEMBER:'instr-arrow',90,0,16,1,1,0,0
MEMBER:'instr-arrow',0,0,16,1,3,0,0
MEMBER:'instr-arrow',0,0,16,4,1,0,0
MEMBER:'instr-arrow',-90,0,16,4,3,0,0
MEMBER:'instr-arrow',180,0,16,6,0,0,0
MEMBER:'instr-arrow',180,0,16,7,0,0,0
MEMBER:'instr-arrow',-90,0,16,7,1,0,0
MEMBER:'instr-input',-1,0,32,0,1,0,0
MEMBER:'instr-grab',-1,1,32,1,1,0,0
MEMBER:'instr-fuse',-1,0,32,4,3,0,0
MEMBER:'instr-output',-1,0,32,5,0,0,0
MEMBER:'instr-sync',-1,0,32,6,0,0,0
MEMBER:'instr-sync',-1,0,32,7,0,0,0
MEMBER:'instr-grab',-1,2,32,7,1,0,0
PIPE:0,4,1
PIPE:0,5,1
PIPE:0,5,2
PIPE:0,5,3
PIPE:0,5,4
PIPE:0,5,5
PIPE:0,4,5
PIPE:0,3,5
PIPE:0,2,5
PIPE:0,1,5
PIPE:0,0,5
PIPE:0,0,6
PIPE:0,0,7
PIPE:1,4,2
PIPE:1,4,3
PIPE:1,4,4
PIPE:1,3,4
PIPE:1,2,4
PIPE:1,1,4
PIPE:1,0,4
PIPE:1,-1,4
PIPE:1,-1,5
PIPE:1,-1,6
PIPE:1,-1,7
PIPE:1,-1,8
PIPE:1,0,8
COMPONENT:'drag-advanced-reactor',17,16,''
MEMBER:'instr-start',180,0,128,3,5,0,0
MEMBER:'instr-start',90,0,32,0,0,0,0
MEMBER:'feature-bonder',-1,0,1,4,3,0,0
MEMBER:'feature-bonder',-1,0,1,5,3,0,0
MEMBER:'feature-bonder',-1,0,1,5,2,0,0
MEMBER:'feature-sensor',-1,0,1,5,4,0,0
MEMBER:'feature-bonder',-1,0,1,0,7,0,0
MEMBER:'instr-arrow',0,0,64,2,1,0,0
MEMBER:'instr-arrow',-90,0,64,2,4,0,0
MEMBER:'instr-arrow',90,0,64,5,1,0,0
MEMBER:'instr-arrow',90,0,64,5,2,0,0
MEMBER:'instr-arrow',0,0,64,5,4,0,0
MEMBER:'instr-arrow',180,0,64,6,2,0,0
MEMBER:'instr-arrow',-90,0,64,6,4,0,0
MEMBER:'instr-arrow',0,0,64,8,1,0,0
MEMBER:'instr-arrow',-90,0,64,8,3,0,0
MEMBER:'instr-arrow',90,0,64,9,1,0,0
MEMBER:'instr-input',-1,1,128,2,5,0,0
MEMBER:'instr-rotate',-1,1,128,2,3,0,0
MEMBER:'instr-grab',-1,1,128,2,4,0,0
MEMBER:'instr-sync',-1,0,128,5,2,0,0
MEMBER:'instr-rotate',-1,0,128,5,4,0,0
MEMBER:'instr-sensor',0,0,128,6,3,0,1
MEMBER:'instr-output',-1,0,128,8,1,0,0
MEMBER:'instr-grab',-1,2,128,8,2,0,0
MEMBER:'instr-arrow',0,0,16,0,1,0,0
MEMBER:'instr-arrow',-90,0,16,0,5,0,0
MEMBER:'instr-arrow',90,0,16,1,1,0,0
MEMBER:'instr-arrow',0,0,16,1,3,0,0
MEMBER:'instr-arrow',90,0,16,3,4,0,0
MEMBER:'instr-arrow',180,0,16,3,5,0,0
MEMBER:'instr-arrow',90,0,16,4,3,0,0
MEMBER:'instr-arrow',180,0,16,4,4,0,0
MEMBER:'instr-input',-1,0,32,0,1,0,0
MEMBER:'instr-grab',-1,1,32,1,1,0,0
MEMBER:'instr-rotate',-1,0,32,1,2,0,0
MEMBER:'instr-bond',-1,0,32,3,4,0,0
MEMBER:'instr-grab',-1,2,32,4,3,0,0
MEMBER:'instr-sync',-1,0,32,4,4,0,0
MEMBER:'instr-arrow',180,0,64,9,5,0,0
MEMBER:'instr-arrow',-90,0,64,2,5,0,0
PIPE:0,4,1
PIPE:0,5,1
PIPE:0,5,2
PIPE:0,5,3
PIPE:1,4,2