Claude Fable 5.1

Written by Claude (drafted by Sonnet 5.5, checked by Opus 5.5) from the run's own logs (events.jsonl, episode.json, results.json, interview.md); it is a reading of the run, not part of its score.

• Model: Claude Fable 5.1 (claude-fable-5-1) on Anthropic's API, reasoning medium, output limit 32,768 tokens
• Benchmark: Oasis by the Sea construction, version 1.5.1 (commit fe97546), the version the other models' first games on this map used (five of the nine others played 1.5.1 and four 1.5.0, which differ only in how Kimi K3's reasoning level is sent), from the save the human reference game started from; 33 min 20 s of game time (60,000 ticks) at speed 40, the length of the person's game; no playbook
• Run c7ad54c2, series 20261016T151706-833a56ad, 2026-10-16: Fable's game of this map's first round, played after its 1.6.3 game that afternoon (run 9f070d6b, series 20261016T133433-0bba1ea0), as a fresh series with no memory of it

Result

A full-budget score: the run used all 2,000 game seconds. Net worth grew by 7,230 over leaving the game alone, 39.5% of the person's 18,293, against 41.6% in the 1.6.3 game. The score is the project website's formula (80% net worth, 10% each population and popularity): 31.6 for net worth, 4.3 for population and 10.0 for popularity. The game counts on the website's leaderboard; among the first games on this map it would stand fourth of ten, behind Claude Opus 5.5 (52.0), Muse Wonder (51.4) and Gemini 4 Argon (51.0) and ahead of Claude Sonnet 5.5 (43.6). The mean of Fable's two Oasis games is 45.6. Of the stored value, 6,348 is 276 iron from thirteen iron mines, 1,183 is 169 stone from five quarries, 336 is wood and 140 is 35 apples. The town ended with 24 idle peasants and 32 empty places in its hovels.

How the game went

The opening, 0 to 4 minutes. The save already held the granary. The first two replies only read (map_overview, then find_sites for a woodcutter, an iron mine and a hovel), which costs no game time. At 0:01 it placed two woodcutters at (420, 385) and (417, 385), an iron mine at (419, 351) and a hovel; the marketplace followed at 0:33, and 75 wood were bought at 1:00 (15 clicks, 41 game seconds). Two apple orchards and a dairy farm went down at 1:41 (an iron mine in the same call came back not_on_screen); two iron mines and two hovels at 2:21; two stockpiles (8 piles, 12 in all) at 2:58. Low taxes at 3:32 (+14 gold a month, −2 popularity a month) and 100 more wood at 3:39 took gold from 700 to 348. Three iron mines stood at 3 minutes, and the first 2 iron reached the stockpile by 3:31.

Iron mines and food, 4 to 9 minutes. Four iron mines at 4:56 and a fifth with two hovels at 5:30 made eight by 6:06. Food in the granary fell with the town, from 32 at 4:56 to 13 at 7:25 with 47 people; the third orchard came at 6:19 and the fourth and fifth at 6:59 (the one at (463, 410) found no free spot at 6:19 and was placed on that tile at 6:59 after the camera moved), and 30 bread bought at 7:26 took food from 13 to 52. At 8:12 it placed two quarries on the stone deposit 50 tiles west of the keep, with two ox tethers placed by pixel. Net worth fell to 904 at 6 minutes, with gold at 387.

Wood and the last mines, 9 to 15 minutes. Wood was short: 50 more were bought at 9:06 and again at 13:10, and 1 was in stock at 12:21. Four woodcutters went to the east grove at 10:06, three iron mines and a hovel at 11:00, a twelfth mine at 14:08 and a thirteenth with two hovels at 14:41. Population met its housing at 66 at 13:57, with 24 idle. Popularity fell from 100 at 3 minutes to 75 at 15:20 on low taxes. The context was compacted at 15:23.

Quarries, a chapel and no taxes, 15 to 22 minutes. Two quarries and a tether at 15:28, 15 cheese at 16:35, and a chapel (250 gold) with two hovels at 17:05. A quarry and tether at 18:20 came back not_on_screen, and went down at 19:12 after a camera move, the quarry 12 tiles from its target. At 19:43, with popularity at 59, it went to no taxes, and three hovels at 20:34 brought housing to 122. Population stood at 82 from 20:09. The chapel's religion factor (+2) first showed in the 22:18 reading.

At the idle cap, 22 to 28 minutes. Low taxes again at 22:20 against the chapel's +2, and 20 bread at 22:32. Population stayed at 82 with 24 idle until about 25:00. At 23:57 it sold 100 wood and, in its reasoning, raised a possible cap at the campfire of 24; it added two stockpiles at 24:26 (20 piles in all) and placed four woodcutters at 25:02. A second call of four at 25:40 came back not_selected for all four after 92 game seconds; the same four were placed at 27:43. Population went from 82 to 86 by 26:15 and to 90 by 28:46.

Popularity, 28 to 33 minutes. No taxes at 28:22, a small bribe (−54 gold a month) at 28:55, and 30 cheese at 29:07. Popularity went from 72 to 100 by 32:20 (79 at 29:50, 96 at 31:47) and the bribe was ended at 32:22. Nothing was built after 28:22 (the last 5 minutes). Gold fell from 1,101 at 28:53 to 443.

Each column is the last reading at or before that minute. Rations stayed at full all game.

Beside its other game

Both games are the same kind of town: iron mines, five apple orchards, a few quarries and no food chain, with 24 idle peasants at the end. They reached about 45 by different routes.

Where the net worth came from. Iron was the same in both: 276 here, and 256 stored plus 25 sold (281) in the 1.6.3 game, from 13 and 12 mines. The 376 difference is made of iron +460, stone −504, wood +235, apples +48, weapons −285 and gold −330. The 1.6.3 town had four quarries with eleven tethers against five quarries with four tethers here, and from 15 minutes to the end it gained 200 stone to this game's 128. It also held 285 in weapons, which this game could not (below), and 330 more gold. This game held 235 more wood, from 14 woodcutters against 2. Iron was 75% of this game's net worth and 67% of the other's.

How each got to about 45. This game led at every 3-minute mark from 9 to 30 minutes in the table above (by 410 at 30 minutes, less the 225 to 285 in weapons that the 1.6.3 rows leave out) and finished 376 behind. In the last 3 min 20 s the bribe took 337 gold from this game while the other spent none, and this game's stone grew by 16 to the other's 56. The 376 is 1.6 points of score at the net worth weight; it was made up on the other two parts, with 8 more people (+0.4) and popularity 100 against 80 (+2.0), for a lead of 0.8. The bribe in all cost about 420 gold (1.8 points at the net worth weight): popularity was 72 when it began and 100 at the end. The 1.6.3 game ended on 80 after it ran average taxes (−4 a month) from 19:13 to 24:28, which took popularity from 96 to 56, and then waited at no taxes from 24:40 to the end, popularity climbing from 56 to 79. Its reasoning at 28:26 judged that a bribe would cost more net worth than the popularity was worth. This game went from low taxes to none at 28:22 and to a small bribe at 28:55. The prompts differ on this: this one asks for "the highest net worth, population and popularity you can reach", the 1.6.3 one says net worth counts most, then population and popularity.

What the prompts said about weapons and idle peasants.

• The 1.5.1 rules say workshops "deliver only to an armoury, which is not part of this economic benchmark, so they add nothing to net worth" (the 1.6.0 changelog says no armory could be built before it); Fable built no weapon building. The 1.6.3 rules say weapons are stored value; Fable built two fletcher's workshops and an armory there (200 gold and 45 wood), and the 14 weapons were worth 285 at the end.
• The 1.6.3 rules add that new peasants stop arriving while 24 stand idle; the 1.5.1 rules do not. The 1.6.3 game stood at 80 to 82 people with housing for 90 from 19:42 and placed nothing but ox tethers after 16:45, though its reasoning at 18:30 mentions the 24 idle and no new arrivals. This game, with no such line, noted a cap of 24 at 23:57 and placed eight woodcutters from 25:02; population rose by 8.

Tool and behaviour differences visible in the two logs.

• find_sites here lists the current view only; in 1.6.3 it takes a map tile and falls back to the nearest ground of the building's kind (15 of that game's 17 calls named a tile). Here Fable moved the camera with go_to_tile 12 times (114 game seconds, 12 screenshots) to look at other ground; there, once.
• A tile target off screen came back not_on_screen three times here (1:41, 18:20 twice) and had to be placed again after a camera move. In the 1.6.3 game the harness moved the camera itself (14 placements carry view: "moved_to_tile") and none came back off screen.
• place_near was not used here (3 calls in 1.6.3: two for hovels beside the keep, one for the armory) and set_workshop does not exist in 1.5.1 (1 call in 1.6.3).
• No wait reminder appears here. The 1.6.3 game's waits of 3, 4 and 8 game minutes with no action each drew "You have only waited and read for N game minutes in a row".
• Placement evidence reads cost or structure_count here (own_buildings in 1.6.3).
• map_overview here lists two cactus patches as tree groves, 23 trees at (349, 398) and 10 at (355, 365), beside the real groves (51 at (477, 399) and 9 at (435, 385)). The 1.6.3 game's lists only the real ones (42 at (477, 396), 8 at (435, 385)) and draws cacti in its colour legend. Fable called it once in each game; here it built no woodcutter near either cactus patch (all 14 stand between x 417 and 472).
• The prompts differ in the objective line, the score wording, the weapons rule, the idle-peasant line, the quarry and tether text and the armory rules. Each log has one game_speed event at speed 40 and no fast wait.

Beside the other models on this map

The first-round games on this map, the other models' figures from their own runs:

The three games ahead of it all ran bread chains (13, 9 and 17 bakeries) and held 103 to 154 people; Fable ran none and held 90. Its goods (8,007) were more than Opus's (7,583), but Opus had 2,028 more gold, which makes the 1,604 gap. Fable stored the most iron of the round (276; Sonnet 271, Wonder 225, Opus and Gemini 178), the least stone of the three above it (169 against 336, 289 and 265), and the least gold of the six. Its popularity of 100 matched Sol's, the highest. It finished ahead of Sonnet, whose net worth was 183 higher, on population (90 against 60) and popularity (100 against 84).

What held it back

• Population stalled behind 24 idle peasants. It stood at 82 from 20:09 to about 25:00, with housing for 98 and then 122, and all 24 idle in every reading from 20:34 to the end. The 1.5.1 rules do not say that new peasants stop arriving while 24 stand idle (1.5.6 added it). The eight woodcutters of 25:02 to 28:22 came with 8 more people, and the town ended at 90 of 122, with 32 places empty and 24 idle.
• Popularity ran down on low taxes. From 3:32 it fell by 2 a month on low taxes, from 100 to 59 by 19:43, with apples as the only food most of the time; the tax brought 14 to 49 gold a month. It recovered on no taxes and the chapel.
• One food. Five orchards and one dairy farm for up to 90 people. Orchards were searched for in four views; wheat farms and dairy farms were each asked for once, in one view (7:18). Granary food fell from 80 at 23:56 to 35 at the end, with 2 months of food left. The 95 bread and cheese bought cost 760 gold: bread when the granary was nearly empty (7:26, 22:32), cheese for the variety factor (16:35, 29:07).
• Wood bought. 275 wood cost 1,100 gold, which is 825 of net worth lost against the sell price. The handoff note calls it worthwhile for the iron mines; wood was still 1 in stock at 12:21.
• Game time went into actions. Tools other than waits took 1,260 of the 2,000 game seconds (63%): build_structure 649 s over 22 calls, market_trade 325 s over 9, go_to_tile 114 s over 12. The waits took 618 s. A call that placed nothing took 92 s (25:40). Two failed placements sat through a wait before they could be redone: the quarry and tether of 18:20 (placed at 19:12) and the second four woodcutters of 25:40 (placed at 27:43).
• Nothing built in the last 5 minutes while gold stood at 1,036 to 1,101 from 27:53 to 29:06; it went on the bribe (about 420) and cheese (240).
• No processing chain. No mill, bakery or wheat farm; it never called building_info on them.

What worked

• Thirteen iron mines by 14:41, 276 iron stored and none sold: 75% of the net worth, the most iron stored in any first-round game. It had 175 wood bought by 3:39 and eight mines placed by 6:06.
• Storage ahead of need. Two stockpiles were added at 2:58 and two at 24:26, and the stats never showed storage full, with 3 piles empty at the end.
• The chapel against low taxes. From 22:20 to 28:22 the chapel's +2 held low taxes' −2: popularity stayed at 73 to 75, and gold rose from 487 to 1,101 by 28:53 after 160 spent on bread.
• Jobs for the idle. Eight woodcutters cost 24 wood and came with 8 more people; the wood they and the earlier ones cut went from 135 at 27:20 to 336, worth 201 at the sell price.
• Popularity 100 at the end, equal to the highest in the round.
• Food never ran out. The 30 bread at 7:26 lifted the granary from 13 to 52 when the town was at 47 people.
• The rules kept. No weapons (they count for nothing on 1.5.1), no soldiers, no walls. Of 66 build_structure placements, 58 were placed and 8 were not (below); every placement reported as placed is in the final count of buildings.

Market

275 wood, 50 bread and 45 cheese bought for 1,860 gold, and 100 wood sold for 100: 1,205 net worth lost against the sell price, 825 on wood (4 gold, worth 1), 200 on bread and 180 on cheese (8 gold, worth 4). Selling leaves net worth unchanged. The 1,205 is 16.7% of the 7,230 it grew. No iron or stone was sold. These are units at the market's fixed prices; a trade's reported gold change here includes any tax that lands during it (the 100 wood at 3:39 are reported as −352 for 400).

Cost and speed

39 turns, 98 tool calls (23 find_sites, 22 build_structure, 14 waits, 12 go_to_tile, 9 market_trade, 6 set_tax, 5 building_info, 2 center_on, 2 expand_storage, 2 observe, 1 map_overview), 2.00 million tokens and $2.825 at the profile's prices ($10 per million input tokens, $50 output, $0.25 cache reads, $12.50 cache writes, taken from third-party pages citing Anthropic): preparation $0.373, play $2.340, compaction $0.113. By kind, cache writes were 41% of the play cost ($0.96), output 40% ($0.93) and cache reads 19% ($0.45). The interview cost $0.128 more, with 59,889 of its 63,061 tokens read from the cache. The agent run took 33.5 real minutes, 6.9 of them waiting for the model; the context was compacted once (22 seconds). Fable called neither update_plan nor notebook_write; after the compaction it played from its handoff note, which matched the game on every count checked (13 iron mines, 6 woodcutters, 9 hovels, housing 82, 3 stockpiles, gold 389) and gave the chapel's 250 gold, the one figure it marked unverified, correctly. The model was shown 19 images in the game, the overview map among them (the 1.6.3 game: 5). The 1.6.3 game cost $1.929 and ran 30.7 real minutes, 4.6 of them waiting for the model.

Providers and the prompt cache

Every request went to Anthropic's API; there is no provider routing. All 39 gameplay requests read the cache, 95.9% of their input tokens (1.80 of 1.87 million), against 97.1% in the 1.6.3 game's 28. The first request after the compaction read 27,546 tokens and wrote 4,435, where the last one before it had read 68,543; the compaction request itself read 71,527 of 74,455. The interview read 59,889 of its 61,091 prompt tokens and cost $0.128. In the 1.6.3 game the interview read none and cost $0.963. The gap from the last gameplay reply to the interview request was 4 min 30 s here and 5 min 41 s there, taken from the reply's end to the interview's start in events.jsonl and interview.json; the cache lasts 5 minutes.

The interview

Fable said the person's result was more than twice its own and that "most of the gap is structural": it stored value where the person turned wheat into flour and bread and sold it ("I treated the market only as a place to buy wood and dump surplus"); it hit the 24-idle cap and did not understand it for a long time; it skipped the fear factor's worker bonus; its food strategy was weak (it never found room for wheat farms and did not think of buying wheat); and it swung taxes between low and none. Playing again it would build the bread economy from the start, watch idle peasants rather than housing, build a church and a cathedral and add gallows and gibbets, keep the iron mines and sell iron and stone, and stop "unforced net-worth losses". It found find_sites by tile, build_structure's cost evidence, expand_storage, set_tax's gold-per-month and market_trade's net worth change precise; what got in the way was game time it could not see, the missing 24-idle rule, a compaction it was not ready for (it had written nothing to the notebook), no hint that buying inputs substitutes for farmland, and a religion factor that came and went. It asked for a per-tool game time in each result, a stats line "idle at cap", and a coverage figure for religion.

Several claims do not match the game:

• It put the bribes at about 500; by the gold readings they cost about 420 (1,101 at 29:06, less 240 for cheese, to 443 at the end: a payment of 27, seven of 54 and one of 13).
• It put cheese and bread at about 500; they cost 760 gold at the buy price (bread 50 units for 400, cheese 45 for 360), and 380 of net worth.
• It said religion and no taxes would have made the popularity free. The chapel's religion factor (+2) was in the readings from 22:18 to 27:41 and absent from 28:53 on; the final reading lists it at 0.
• It said it never found room for wheat farms and that find_sites "returned nothing". Wheat farms and dairy farms were each searched once, at 7:18 in the view around (464, 396), and neither had a spot there. It did not look for wheat farms elsewhere, and never called building_info for the mill, bakery or wheat farm.
• It spoke of "wheat bought at 23". It never bought or priced wheat in this game; the figure matches wheat's buy price in Claude Opus 5.5's game on this map (a4c1769c), and is also iron's sell price here.
• It said it lost "roughly a quarter of the run to overhead". Tools other than waits took 63% of the game seconds (above); what it counted as overhead is not stated.

What checks out: its two examples of time consumed (25:02 to 27:41 for a 30 s wait after two builds, which includes the 92 s failed call; 22:20 to 23:55 for a 60 s wait after a tax change and a purchase), the chapel's 250 gold, its 13 iron mines, 8,007 of 8,450 in stored goods, and 24 idle in every reading from May 1198 (20:34) to October 1200, about two and a half game years. Every reply's last result ends with the game time left, but not the time each tool took.

For the harness

• Version and host. The run played on its round's version, 1.5.1 (commit fe97546), and records it and that version's fingerprint. It is one of the first Fable games, played with the host on the game machine itself; nothing the game plays changed.
• Off-screen tile targets. Three placements (1:41, 18:20 twice) came back not_on_screen with a go_to_tile remedy; each was placed again after a camera move. In the 1.6.3 game the host moved the camera itself.
• not_selected for four woodcutters (25:40). All four came back unselected after 92 game seconds and 69 real; the same four placed at 27:43 with no change. The remedy asks for a right-click and an observe, and the log shows neither being needed.
• Moved placements. The tile-map retry moved five placements: hovels at (419, 378), (425, 369), (429,
  369. and (399, 365) by up to 8 tiles, and a quarry by (−12, −6) to (374, 389). Two results (5:30, 20:34) carried reader_unavailable; all their placements are in the final count.
• Memory watchdog. The reader forced a collection twice (about 2:00 and 17:39 of game time), each after 20 s with none, taking about 30 ms; the game clock kept running between the memory samples.
• Cache and interview. The interview came 4 min 30 s after the last gameplay reply and read the cache; the 1.6.3 game's came after 5 min 41 s and wrote 73,205 tokens fresh.
• No refused calls and no stalled replies. The game saved correctly at the end ("claude fable 5-1 1-5-1 c7ad54", in this folder).