SpaceChem Bench: Slightly Different
Inputs: β Hydrogen (H2). Output: ω Hydrogen (H2) ×10.
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. 15 of 16 models solved it. Together they found 2 new Pareto-frontier points beyond the frozen community archive.
Records
| Score | Community best | Best LLM | Model |
|---|---|---|---|
| Cycles | 45 | 47 | GPT-6.1 Sol · +4% |
| Reactors | 1 | 1 | DeepSeek V4.1 Flash Ties record |
| Symbols | 6 | 6 | DeepSeek V4.1 Flash 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 ↙Search over time
Loading puzzle trajectories…
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 | 48 | 1 | 6 | 2 |
| 02GPT-6.1 Sol | Yes | 47 | 1 | 6 | 1 |
| 03Muse Wonder 1.0 | Yes | 52 | 1 | 6 | 1 |
| 04Fable 5.1 | Yes | 52 | 1 | 6 | — |
| 05Gemini 4 Argon | Yes | 52 | 1 | 6 | — |
| 06Opus 5.5 | Yes | 52 | 1 | 6 | — |
| 07DeepSeek V4.1 Flash | Yes | 57 | 1 | 6 | — |
| 08Sonnet 5.5 | Yes | 57 | 1 | 6 | — |
| 09Kimi K3.1 Pro | Yes | 59 | 1 | 6 | — |
| 10Gemini 3.8 Flash | Yes | 62 | 1 | 6 | — |
| 11Grok 4.7 | Yes | 62 | 1 | 6 | — |
| 12Muse Spark 1.3 | Yes | 63 | 1 | 6 | — |
| 13GPT-6 Luna | Yes | 107 | 1 | 6 | — |
| 14Haiku 5.5 | Yes | 116 | 1 | 6 | — |
| 15GLM-5.3 | Yes | 117 | 1 | 6 | — |
| 16MiMo-V2.6-Pro | 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-6.1 Sol
47 cycles · 1 reactor · 12 symbolsresearch_tutorial_1.47-1-12.txt on GitHub
Layout
Running in the game

SpaceChem Community Edition export (research_tutorial_1.47-1-12.txt)
SOLUTION:Slightly Different,Player,0-0-0
COMPONENT:'empty-research-reactor',2,0,''
MEMBER:'instr-start',0,0,128,4,5,0,0
MEMBER:'instr-start',90,0,32,2,4,0,0
MEMBER:'instr-arrow',0,0,64,2,5,0,0
MEMBER:'instr-arrow',180,0,64,6,5,0,0
MEMBER:'instr-grab',-1,0,128,2,5,0,0
MEMBER:'instr-rotate',-1,0,128,3,5,0,0
MEMBER:'instr-input',-1,1,128,5,5,0,0
MEMBER:'instr-grab',-1,0,128,6,5,0,0
MEMBER:'instr-arrow',0,0,16,2,5,0,0
MEMBER:'instr-arrow',180,0,16,6,5,0,0
MEMBER:'instr-grab',-1,0,32,2,5,0,0
MEMBER:'instr-output',-1,1,32,3,5,0,0
MEMBER:'instr-rotate',-1,0,32,5,5,0,0
MEMBER:'instr-grab',-1,0,32,6,5,0,0
GPT-6 Astra
115 cycles · 1 reactor · 6 symbolsresearch_tutorial_1.115-1-6.txt on GitHub
Layout
Running in the game

SpaceChem Community Edition export (research_tutorial_1.115-1-6.txt)
SOLUTION:Slightly Different,Player,0-0-0
COMPONENT:'empty-research-reactor',2,0,''
MEMBER:'instr-start',90,0,128,0,4,0,0
MEMBER:'instr-start',180,0,32,1,0,0,0
MEMBER:'instr-arrow',0,0,64,0,5,0,0
MEMBER:'instr-arrow',180,0,64,6,5,0,0
MEMBER:'instr-input',-1,1,128,0,5,0,0
MEMBER:'instr-grab',-1,0,128,1,5,0,0
MEMBER:'instr-grab',-1,0,128,6,5,0,0
MEMBER:'instr-output',-1,1,32,0,0,0,0