SpaceChem Bench: Ice to Meet You

fusion_1 Medium Fusion Single-reactor Sikutar · SpaceChem Bench report →

Inputs: α Hydrogen (H), β Iron (II) Oxide (FeO). Output: ψ Cobalt (II) Oxide (CoO) ×10. Features: Bonders (4), Fuser.

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. 16 of 16 models solved it. Together they found 1 new Pareto-frontier point beyond the frozen community archive.

16 / 16models solved it
56best LLM cycles (44 community)
1new frontier point

Records

ScoreCommunity bestBest LLMModel
Cycles4456GPT-6 Astra · +27%
Reactors11DeepSeek V4.1 Flash Ties record
Symbols1010DeepSeek 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 ↙
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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 5.5Yes721111
02Fable 5.1Yes741111
03GPT-6 AstraYes56110—
04GPT-6.1 SolYes56111—
05Gemini 4 ArgonYes73111—
06Sonnet 5.5Yes74111—
07DeepSeek V4.1 FlashYes77110—
08Gemini 3.8 FlashYes83111—
09Kimi K3.1 ProYes86111—
10Muse Spark 1.3Yes93112—
11Muse Wonder 1.0Yes105111—
12GLM-5.3Yes130112—
13Grok 4.7Yes136113—
14Haiku 5.5Yes136115—
15MiMo-V2.6-ProYes231112—
16GPT-6 LunaYes485146—

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 Fewest cyclesFewest reactors

56 cycles · 1 reactor · 35 symbolsfusion_1.56-1-35.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← FUSE S← IN β B+ GRAB GRAB IN α FUSE IN α FUSE IN β IN β B− FUSE IN β DROP DROP OUT ψ IN α OUT ψ IN α B+ B−

Running in the game

GPT-6 Astra solution running on fusion_1 in SpaceChem
SpaceChem Community Edition export (fusion_1.56-1-35.txt)
SOLUTION:Ice to Meet You,Player,0-0-0
COMPONENT:'drag-fusion-reactor',2,0,''
MEMBER:'instr-start',180,0,128,3,5,0,0
MEMBER:'instr-start',180,0,32,7,1,0,0
MEMBER:'feature-bonder',-1,0,1,1,4,0,0
MEMBER:'feature-bonder',-1,0,1,1,5,0,0
MEMBER:'feature-bonder',-1,0,1,6,0,0,0
MEMBER:'feature-bonder',-1,0,1,6,1,0,0
MEMBER:'feature-fuser',-1,0,1,1,1,0,0
MEMBER:'instr-arrow',0,0,64,1,2,0,0
MEMBER:'instr-arrow',-90,0,64,1,5,0,0
MEMBER:'instr-arrow',0,0,64,2,0,0,0
MEMBER:'instr-arrow',-90,0,64,2,2,0,0
MEMBER:'instr-arrow',90,0,64,6,0,0,0
MEMBER:'instr-arrow',180,0,64,6,5,0,0
MEMBER:'instr-input',-1,1,128,1,4,0,0
MEMBER:'instr-grab',-1,1,128,1,5,0,0
MEMBER:'instr-input',-1,0,128,2,0,0,0
MEMBER:'instr-input',-1,0,128,2,1,0,0
MEMBER:'instr-input',-1,1,128,2,5,0,0
MEMBER:'instr-input',-1,1,128,3,0,0,0
MEMBER:'instr-bond',-1,1,128,4,5,0,0
MEMBER:'instr-input',-1,1,128,5,0,0,0
MEMBER:'instr-grab',-1,2,128,6,0,0,0
MEMBER:'instr-output',-1,0,128,6,1,0,0
MEMBER:'instr-input',-1,0,128,6,2,0,0
MEMBER:'instr-input',-1,0,128,6,3,0,0
MEMBER:'instr-arrow',0,0,16,1,2,0,0
MEMBER:'instr-arrow',-90,0,16,1,5,0,0
MEMBER:'instr-arrow',0,0,16,2,0,0,0
MEMBER:'instr-arrow',-90,0,16,2,2,0,0
MEMBER:'instr-arrow',90,0,16,6,0,0,0
MEMBER:'instr-arrow',90,0,16,6,1,0,0
MEMBER:'instr-arrow',180,0,16,6,5,0,0
MEMBER:'instr-bond',-1,1,32,1,3,0,0
MEMBER:'instr-bond',-1,0,32,1,4,0,0
MEMBER:'instr-grab',-1,1,32,1,5,0,0
MEMBER:'instr-fuse',-1,0,32,2,0,0,0
MEMBER:'instr-fuse',-1,0,32,2,1,0,0
MEMBER:'instr-fuse',-1,0,32,3,5,0,0
MEMBER:'instr-fuse',-1,0,32,4,5,0,0
MEMBER:'instr-grab',-1,2,32,6,0,0,0
MEMBER:'instr-output',-1,0,32,6,2,0,0
MEMBER:'instr-bond',-1,0,32,6,3,0,0

GPT-6 Astra Fewest symbols

176 cycles · 1 reactor · 10 symbolsfusion_1.176-1-10.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← IN β B+ GRAB IN α FUSE OUT ψ

Running in the game

GPT-6 Astra solution running on fusion_1 in SpaceChem
SpaceChem Community Edition export (fusion_1.176-1-10.txt)
SOLUTION:Ice to Meet You,Player,0-0-0
COMPONENT:'drag-fusion-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',-1,0,1,0,5,0,0
MEMBER:'feature-bonder',-1,0,1,1,5,0,0
MEMBER:'feature-fuser',-1,0,1,5,3,0,0
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',0,0,64,0,5,0,0
MEMBER:'instr-arrow',180,0,64,5,1,0,0
MEMBER:'instr-arrow',-90,0,64,5,5,0,0
MEMBER:'instr-input',-1,1,128,0,4,0,0
MEMBER:'instr-bond',-1,0,128,0,5,0,0
MEMBER:'instr-grab',-1,1,128,1,1,0,0
MEMBER:'instr-input',-1,0,128,2,1,0,0
MEMBER:'instr-fuse',-1,0,128,5,3,0,0
MEMBER:'instr-output',-1,0,32,0,0,0,0