Benchmark Almanac

Time Horizon Index: KSP

Claude Opus 5.5 91.3% leads since Sep 2026 Not in model cards

Agents get five days to build and run a space program in Kerbal Space Program. The score is progress through 30 fixed missions.

Vals estimates a human needs 90 to 120 hours for the first 28 missions. 13 models on 2026-10-07, led by Claude Opus 5.5 at 91.33%.

Made by Vals AI Released Jul 2026 Video games Tasks kept private Last model added Sep 2026 Scores refreshed 2 Nov 2026
Level
Expert Specialists with years of training, often over hours of work
Scored
Checked automatically A program checks the result against an answer key, unit tests or the expected final state.
Answers
Agent task Many steps in a terminal, browser, desktop, app, game or robot.
Leaderboard
13
Models scored on its own leaderboard

Claude Opus 5.5 leads with 91.3%

Best score per model from the benchmark's own leaderboard, read on 2 Nov 2026. Where a model ran with several settings or harnesses, we keep its best.

13 models. Scroll sideways for the rest.

  1. 91.3 Claude Opus 5.5
  2. 90.5 GPT-6 Astra
  3. 63.3 Claude Fable 5.1
  4. 52.5 Gemini 4 Argon
  5. 23.8 GPT-5.6 Sol
  6. 18.8 Claude Opus 5
  7. 18.8 Gemini 3.8 Flash
  8. 11.8 Claude Opus 4.8
  9. 10.5 Kimi K3
  10. 8.33 GPT-5.5
  11. 6.33 Grok 4.5
  12. 5.83 Grok 4.6
  13. 1.67 Muse Spark 1.1
  1. 1 Claude Opus 5.5 91.3%
  2. 2 GPT-6 Astra 90.5%
  3. 3 Claude Fable 5.1 63.3%
  4. 4 Gemini 4 Argon 52.5%
  5. 5 GPT-5.6 Sol 23.8%
  6. 6 Claude Opus 5 18.8%
  7. 7 Gemini 3.8 Flash 18.8%
  8. 8 Claude Opus 4.8 11.8%
  9. 9 Kimi K3 10.5%
  10. 10 GPT-5.5 8.33%
  11. 11 Grok 4.5 6.33%
  12. 12 Grok 4.6 5.83%
  13. 13 Muse Spark 1.1 1.67%
#ModelScoreSettingDateSource
1 Claude Opus 5.5 91.3% Sep 2026 Official leaderboard
2 GPT-6 Astra 90.5% Sep 2026 Official leaderboard
3 Claude Fable 5.1 63.3% Sep 2026 Official leaderboard
4 Gemini 4 Argon 52.5% Sep 2026 Official leaderboard
5 GPT-5.6 Sol 23.8% Jul 2026 Official leaderboard
6 Claude Opus 5 18.8% Jul 2026 Official leaderboard
7 Gemini 3.8 Flash 18.8% Sep 2026 Official leaderboard
8 Claude Opus 4.8 11.8% May 2026 Official leaderboard
9 Kimi K3 10.5% Jul 2026 Official leaderboard
10 GPT-5.5 8.33% Apr 2026 Official leaderboard
11 Grok 4.5 6.33% Jul 2026 Official leaderboard
12 Grok 4.6 5.83% Aug 2026 Official leaderboard
13 Muse Spark 1.1 1.67% Jul 2026 Official leaderboard

5 models have held number one since its release in Jul 2026

Lab claims count from the day the card came out, independent runs from the model’s release.

Anthropic OpenAI
Own leaderboard Passed 85% in Sep 2026, by GPT-6 Astra
Claude Opus 5.5 91.3%

The best score passed 85% in Sep 2026

All the scores we have, one dot each, so a model tested at several settings appears more than once.

On the benchmark’s own leaderboard Best so far
0% 20% 40% 60% 80% 100% 2026 Near the ceiling (85%) Claude Opus 5.5 Claude Fable 5.1 GPT-5.6 Sol Claude Opus 4.8 0% 20% 40% 60% 80% 100% 2026 Near the ceiling (85%) Claude Opus 5.5 Claude Fable 5.1

No lab model card reports it yet

We read the headline results of 479 launch posts from 51 labs, and none of them list this benchmark.

More in Games and long tasks

All 68 in Games and long tasks
  • ARC-AGI-3 In use Interactive game environments where agents must explore, infer goals and rules, and act efficiently without instructions. GPT-6 Astra 100%
  • MineDojo Fading Agents complete open-ended tasks in Minecraft, such as mining blocks and fighting mobs, from a large simulation suite. Programmatic checks score many tasks. Seed2.0 Pro 49%
  • Orak Fading LLM agents play 12 popular video games across most genres through an MCP interface. Scores come from in-game progress or outcomes per title. Nemotron 3 Nano 4B 22.9
  • GameWorld Only in system cards Multimodal game agents play 34 browser games across 170 tasks. Outcomes are checked from the game state. Gemini 3 Flash 41.9%
  • Swarm Bench Only in system cards Models orchestrate agent swarms on complex tasks that benefit from coordinated decomposition and parallel execution. Kimi K3 76.3%
  • TextQuests Only in system cards Agents play 25 classic interactive fiction games. Measures game progress and harmful actions per 100 steps. Muse Spark 2.40