--- title: "GPT-5.6 Terra plays Tokyo 1957 (seed 1) | Micropolis run | Evals by Jetty" url: https://evaljetty.com/micropolis/runs/gpt56terra-tokyo-s1.html description: "GPT-5.6 Terra as mayor in Micropolis, Tokyo 1957: monster attack: won, city score 501. Timelapse, charts, every decision and the run's evaluation." updated: 2026-09-28 publisher: Jetty (https://jetty.io) --- 02 — Run · Round 1 · Tokyo 1957: monster attack · gpt56terra-tokyo-s1 # GPT-5.6 Terra plays Tokyo 1957 A monster attacks Tokyo in 1957. Rebuild and get the city score above 500 within 5 years. Ended Jan 1962: won, city score 501. [Decision log](https://evaljetty.com/micropolis/runs/gpt56terra-tokyo-s1/decisions.jsonl)[City stats (CSV)](https://evaljetty.com/micropolis/runs/gpt56terra-tokyo-s1/series.csv)[Save file (.cty)](https://evaljetty.com/micropolis/runs/gpt56terra-tokyo-s1/city.cty)[Final map (PNG)](https://evaljetty.com/micropolis/runs/gpt56terra-tokyo-s1/final_map.png)[Runtime config](https://evaljetty.com/micropolis/runs/gpt56terra-tokyo-s1/runtime_config.json)[Validation report](https://evaljetty.com/micropolis/runs/gpt56terra-tokyo-s1/validation_report.json) GOAL MET seed 1 GPT-5.6 Terra openai/gpt-5.6-terra WON: City score 501 (goal > 500); engine verdict: won Population (start → end)113,100 → 29,640 Peak population113,100City score (start → end)500 → 501 Funds at the end$0Crime / pollution / traffic27 / 47 / 4 Zones R / C / I129 / 97 / 76 Power plants (coal / nuclear)4 / 1Police / fire stations16 / 7 Turns (model / failed)20 (20 / 0) Actions applied / rejected135 / 25 Mean turn latency17.9sModel cost$0.614Wall clock6.0 min Jetty run ID00ff7869 ## The city over time ### Population People, after every turn ### Funds Treasury, after every turn ### City score 0–1000, re-evaluated each January Table view | Turn | Date | Population | Funds | City score | Crime | Pollution | | --- | --- | --- | --- | --- | --- | --- | | 0 | Jan 1957 | 113,100 | $20,000 | 500 | 31 | 64 | | 1 | Apr 1957 | 106,880 | $18,461 | 668 | 31 | 64 | | 2 | Jul 1957 | 100,460 | $18,026 | 668 | 90 | 63 | | 3 | Oct 1957 | 94,660 | $17,955 | 668 | 98 | 66 | | 4 | Jan 1958 | 89,140 | $15,405 | 427 | 98 | 66 | | 5 | Apr 1958 | 84,480 | $9,273 | 427 | 91 | 64 | | 6 | Jul 1958 | 81,500 | $9,052 | 427 | 63 | 66 | | 7 | Oct 1958 | 77,340 | $8,214 | 427 | 63 | 66 | | 8 | Jan 1959 | 78,220 | $5,352 | 540 | 56 | 61 | | 9 | Apr 1959 | 74,000 | $5,173 | 540 | 55 | 59 | | 10 | Jul 1959 | 69,240 | $5,067 | 540 | 55 | 57 | | 11 | Oct 1959 | 61,420 | $5,067 | 540 | 50 | 57 | | 12 | Jan 1960 | 55,940 | $3,778 | 444 | 43 | 54 | | 13 | Apr 1960 | 51,180 | $3,756 | 444 | 43 | 50 | | 14 | Jul 1960 | 47,260 | $678 | 444 | 39 | 50 | | 15 | Oct 1960 | 43,460 | $678 | 444 | 36 | 51 | | 16 | Jan 1961 | 39,920 | $0 | 382 | 36 | 48 | | 17 | Apr 1961 | 35,560 | $0 | 382 | 33 | 49 | | 18 | Jul 1961 | 32,640 | $0 | 382 | 30 | 49 | | 19 | Oct 1961 | 29,040 | $0 | 382 | 30 | 48 | | 20 | Jan 1962 | 30,200 | $0 | 501 | 27 | 47 | ## Final map [![Final city map: GPT-5.6 Terra on Tokyo 1957: monster attack](https://evaljetty.com/micropolis/media/gpt56terra-tokyo-s1-map.jpg)](https://evaljetty.com/micropolis/runs/gpt56terra-tokyo-s1/final_map.png) ## Evaluation passchecks **10/10** verdict: valid run (code checks and checklist) and task goal met (judge) | Status | Kind | Check | Detail | | --- | --- | --- | --- | | pass | step | environment | Environment check (snapshot, engine, key) | | pass | step | launch | Launch run-city as a detached process | | pass | step | supervise | Supervise in the foreground until run-city exits | | pass | step | render | Timelapse video rendered | | pass | step | notes | Append Notes to summary.md | | pass | code\_check | outputs-exist | all present | | pass | code\_check | sim-reached-deadline | ended Jan 1962 after 20 turns; scenario verdict True | | pass | code\_check | decisions-logged | 20 rows for 20 turns | | pass | code\_check | llm-turns-valid | 0/20 model turns failed | | pass | code\_check | video-decodes | duration 30.0s | | pass | code\_check | limits-respected | 6.0 wall-minutes (model budget 45.0 min) | | pass | judge | scenario-goal | WON: City score 501 (goal > 500); engine verdict: won (score 1 / threshold 1) | | pass | checklist | notes-explain-outcome | summary.md has Notes section explaining the score-501 win, citing model thoughts from turns 1, 8, and 20 | | pass | checklist | player-matches-request | result.json confirms player=gpt56terra, task=tokyo, seed=1 matching runbook parameters | | pass | checklist | no-silent-outage | run.log shows 20 consecutive successful turns with 0 LLM failures, no gaps or error stretches | ## Decision timeline What the mayor thought and did each turn. Click a turn to jump the timelapse there. --- Source: https://evaljetty.com/micropolis/runs/gpt56terra-tokyo-s1.html · Evals by Jetty · Run your own evals: https://jetty.io/?utm_source=evaljetty&utm_medium=llms