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: Large Barren Desert construction, version 1.6.3 (commit 1d0c697), 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 edc045df, series 20261016T141734-c9d76aca, 2026-10-16: Fable's game on this map with version 1.6.3, a fresh series with no memory of its other games. Its other desert game, on 1.5.6, is still running.

Result

A full-budget score: the run used all 2,000 game seconds. Net worth ended 440 below leaving the game alone, −9% of the person's growth of 4,792. The score is the project website's formula (80% net worth, 10% each population and popularity): −7.3 from net worth, +1.7 from population and +5.0 from popularity. The game counts on the website's leaderboard. The 5,192 of leaving the game alone leaves out the part of the starting package that waits for storage room (about 1,150 at the sell price, per docs/benchmark.md), which this game took in; against the whole package, about 6,500 by the rules, the town ended about 1,750 lower.

The stored goods are 49 iron (1,127), 36 swords (1,080), 34 pikes (612), 14 crossbows (420), 13 metal armour (390), 50 stone (350), 20 ale (200), 20 pitch (200), 19 spears (190) and 3 bows (45). The stone, ale and pitch (750) came with the start and were never touched. The town ended with 24 idle peasants and 21 free places in its hovels, no food, and popularity falling (food −8, tax +1).

How the game went

Times are game time; for a call, when it began.

An opening on iron, 0 to 4 minutes. map_overview in its first reply (0:01) listed stone 83 to 106 tiles west of the keep and iron ore 57 to 69 tiles east, and no farmland, oil or tree groves. A marketplace at 0:01, three hovels at 0:15 and three stockpile piles at 0:39, then find_sites and four iron mines at 1:18, all placed by 1:59 (the four spots find_sites returned; a second search near (560, 395) at 2:02 found none within 25 tiles). At 2:09 it asked for an armory by the keep, two blacksmith's workshops, an armorer's workshop and three hovels: the armory and the armorer's found no room in view, the blacksmith's went up (400 gold) and one hovel followed at 2:52. It bought 30 cheese (3:09) and 30 apples (3:35), 480 gold, for food variety. At 4:04 the town had 34 people, 24 of them idle.

The weapons wing, 4 to 12 minutes. At 4:07 find_sites gave an armory spot, and it built the armory, an armorer's, a fletcher's and a poleturner's workshop, bought 100 planks (4:43) and set mean taxes at 5:50 (popularity −8 a month, 44 gold a month). At 6:12 two more poleturner's and two more fletcher's workshops, at 6:48 three hovels, at 7:31 average taxes and at 7:43 60 meat. Six set_workshop calls (8:26 to 10:17) set the poleturners to pikes and the fletchers to crossbows. At 10:24 it ended taxes (popularity had fallen from 100 to 63), at 10:38 it built four more poleturner's workshops, at 11:17 a second armory and at 11:39 it bought 75 planks. Those were its last buildings but for a third armory at 24:30: 7 poleturner's, 3 fletcher's, 2 blacksmith's and an armorer's workshop in all, with 4 iron mines and 7 hovels. The taxes of this stretch brought 387 gold.

Food and rations, 12 to 29 minutes. 100 meat at 12:41 (the 20 clicks took 68 game seconds). Of four set_workshop calls for the new poleturners, three set pikes and one opened a hovel drawn over the workshop (13:49, and again by pixel at 15:07), so that poleturner was left on the default, spears (the other results read "making: spears" before the change). Then a 120-second wait, half rations at 17:15 (popularity 76, food 49), 60 meat at 19:59 and 50 planks at 20:51, extra rations at 22:35 (popularity 42), half again at 24:18 with a third armory and 60 meat, extra at 27:23 (popularity 41) and full at 29:27. Gold stood at 1,427 from 14:00 to 19:59 and was 267 by 25:42. Popularity went under 50 twice (21:26 to 23:33, low 41; 26:07 to 28:20, low 40) and each time 8 or 9 of the 45 people left and then came back. It made 11 replies after 11:39 and built nothing in them but the armory.

The end, 29 to 33 minutes. 30 meat at 29:39 took gold from 267 to 27; low taxes at 30:08 brought 98 gold in two minutes and it set no taxes at 32:00. The reply at 32:00, with 80 seconds left and food at 13, waited out the rest. Food ran out at 32:46, and popularity went from 58 to 50 in the last 34 seconds.

Each column is the last reading at or before that minute. Up to 30 minutes the net worth row counts gold, wood, stone, iron and food (at 4) as the recording logs them; weapons, ale and pitch are left out, so it reads low. At 29:26 the armory held 2,321 of weapons and armour, which with the ale and pitch (400) puts the 30-minute figure near 4,400, not 1,645.

Where the starting gold went. The 5,000 gold arrived by 0:30.

5,000 − 2,960 − 900 − 1,500 + 498 = 138. Nothing was sold. The 498 is every rise in the gold reading once the package was paid in: 159 under mean taxes (6:05 to 7:43), 228 under average (to 10:38), 98 under low (30:18 to 32:12) and 13 after.

The goods: about 245 wood came with the start and 225 were bought. About 332 went into buildings (iron mines 80, hovels 42, workshops 190, armories 15, marketplace 5; the blacksmith's 20 each from the game reference) and about 135 into weapons (by the reference's inputs per piece: pikes 2, crossbows 3, spears 1, bows 2), together 467 against 470, which fits the stock being empty at the end. The mines delivered about 83 iron on top of the starting 15: 36 swords and 13 armour took 49 (one each, per the reference) and 49 are in store. The start's 55 meat was eaten; the 50 stone, 20 pitch and 20 ale are still there.

Beside its other games

Its 1.5.6 game on this map is still running, so there is nothing to set beside this one yet; the map's score for Fable will be the mean of the two. Its other three games that day were on other maps, each a fresh series:

On Oasis by the Sea it put its gold into iron mines and quarries; here find_sites found room for four iron mines, the map has no farms or trees, and its gold went into workshops and bought food. It made 23 replies here, against 28 to 48 there.

Beside the other models

The 1.6.3 round on this map, by the website's formula: GPT-6.1 Sol 98.3 (net worth 10,289), Gemini 4 Argon 51.3 (7,494), Claude Opus 5.5 43.3 (7,659), Claude Sonnet 5.5 41.5 (7,127), Claude Haiku 5.5 20.1 (5,721), GLM 5.3 Flash 12.6 (5,275), Kimi K3 2.7 (5,050), Fable −0.7 (4,752) and GPT-6 Luna −3.4 (4,409); Muse Wonder has no 1.6.3 game here. Fable is eighth of nine, and one of three below leaving the game alone (Kimi, Fable, Luna), each with 13 to 19 weapon workshops and a town of 45 to 63 people.

The four above 40 all built quarries (Sol and Opus 10, Gemini 13, Sonnet 4) and ended with 118 to 530 stone; Fable built none and held its starting 50. Opus built ten weapon workshops, about Fable's number, and ten quarries with 21 ox tethers: its 490 stone alone were worth 3,430 and it ended 2,907 above Fable.

GPT-6 Luna's 1.6.3 game is the nearest: four iron mines, no quarry, a weapons wing, 24 idle peasants and a net worth under leaving the game alone.

(Luna's workshop gold and tax income are from the game reference's costs and the gold left over after its purchases, sales and building costs; its recording's gold gains less the sales give 3,383.)

Both put the starting gold into workshops and bought food at 8 (worth 4) for a town that stalled with 24 idle peasants, and both mined about the same iron (Fable about 83, Luna about 80). The differences: Luna's wing was larger and made less, 63 pieces from 19 workshops against Fable's 119 from 13, and it bought more planks (550 against 225). It also built an inn (+4) and a chapel (+2) in its first two minutes, kept popularity at 76 to 98 from 3 minutes on and taxed all game (about 3,500 gold; 50 a month at high taxes at the end). Fable had neither, taxed for about 15 of the 75 game months at 26 to 44 gold a month, and swung its popularity between 40 and 76 with rations. Luna ended with more gold and less stored value; Fable ended 343 higher.

What held it back

• Food bought, then eaten. 370 food for 2,960 gold, 77% of everything it bought and 59% of the starting gold; it was worth 1,480 when it arrived and nothing at the end. The 45 people ate about 7 food a game month at full rations (food fell from 44 to 18 between 11:14 and 12:52). It never sold anything: at 29:26 it had 267 gold, 32 swords (960) and 44 iron (1,012) in store, and 27 gold at 30:08.

• A wing that returned less than it cost. The 13 workshops and 3 armories cost 1,500 gold and about 205 wood (about 1,700 at the sell price). They made 2,737 from about 135 wood and 49 iron (1,262), a gain of 1,475, about 230 less than they cost; the metal ones gained 343 on 49 iron for 500 gold.

  	Built	Gold	Made, at the sell price
  Poleturner's	7	700	34 pikes, 19 spears: 802
  Fletcher's	3	300	14 crossbows, 3 bows: 465
  Blacksmith's	2	400	36 swords: 1,080
  Armorer's	1	100	13 metal armour: 390

  From 12:41 the armory filled at about 4.7 pieces a minute (22 held then, 119 at the end), about 108 a minute in value, close to the 2,200 gold it spent on food and planks in the same time. The four iron mines, which cost 80 wood, made 1,909 of iron.

• 24 idle peasants from 4:04 and no job-giving building after 11:17. The 4 mines and 13 workshops gave 21 jobs for 45 people with 21 places free. At 14:56 the reply judged that more workshops would add population but not output, and it built none. The prompt says arrivals stop while 24 stand idle.

• No stone. The stone lay 83 to 106 tiles west; its opening plan listed "Quarries + ox tethers on the western stone if time/workers allow, otherwise skip (far away, low value)", and it built none. The four games above 40 all had stone.

• Popularity by rations and taxes alone. Mean and average taxes took popularity from 100 to 62 by 10:30 for 387 gold, and the +2 variety factor from the cheese and apples was gone between 7:32 and 10:24. Rations changed five times (full, half, extra, half, extra, full); the half-ration stretches dropped popularity under 50 twice and cost 8 or 9 people each time. At 12:41 it looked up the chapel (250 gold) and the inn (20 wood and 100 gold), and built neither, though it held the 20 ale an inn would use.

• Food ran out in the last 34 seconds. See below.

When food ran out, and whether it noticed. Food reached 0 at 32:46. The observation it received at 32:00 (80 seconds left) showed food 13 at full rations, about 50 seconds' worth; its reply read "Final stretch: 80 seconds left. Set no taxes to hold popularity, and let the run finish." and mentioned no food. It had 125 gold, enough for three lots, and 34 swords it could have sold. It kept no plan or notes (the plan and notebook are empty). Version 1.6.3 has no warning for low food or falling popularity, and the observation's game events were empty. At 29:27 its reasoning counted "roughly 8 months" in the 3.9 minutes left and aimed at 55 food by buying 30 meat; the dates in the observations (October 1177 at 29:26, July 1178 at the end) give 9 months, at about 26.6 game seconds each (72 months from April 1172 at 0:01 to April 1178 at 32:00) where the prompt says about 29. The purchase also left 43, not 55, because people ate during its 29 seconds. Popularity went from 58 at 32:30 to 55 at 33:00 and 50 at the end; 8 points are 0.8 of a score point.

What worked

• Mines first, by tile. Four iron mines placed by 1:59 from map_overview and find_sites without a screenshot, using every iron site the search found; they mined about 83 iron over the game.
• The armory had room. It never ran short (50, 100, then 150 places, 119 held); 31 of 35 placements went through, the four that did not (an armory, an armorer's workshop and two hovels) for want of room, and no call was refused.
• Food held until the last minute. Five meat purchases kept the granary from running below 18 for 32 minutes, and extra rations lifted popularity from the low 40s to 61 and 66.
• set_workshop by tile. Of 11 calls 9 set a product; the two failures were a hovel drawn over one workshop.

Market

30 cheese, 30 apples, 310 meat and 225 planks bought for 3,860 gold; nothing sold. The purchases lost 2,155 net worth against the sell price (food 8 for 4, planks 4 for 1; selling leaves net worth unchanged). These are units at the market's fixed prices. The ten calls were 119 clicks and took 463 game seconds, 3.9 seconds a click (20 lots in 67 and 68 seconds).

Cost and speed

23 turns, 72 tool calls (12 waits, 11 set_workshop, 10 market_trade, 7 find_sites, 6 place_near, 5 build_structure, 5 set_tax, 5 set_rations, 4 building_info, 3 observe, 3 expand_storage, 1 map_overview), 1.25 million tokens and $1.824 at the profile's prices (preparation $0.455, play $1.369, no compaction). The prices are $10 per million input tokens, $50 output, $0.25 cache read and $12.50 cache write. The interview cost about $0.946 more, none of its 71,089 tokens read from the cache (see below). The agent run took 29.6 real minutes, 3.6 of them waiting for the model (longest reply 16 seconds); the context was never compacted (70,888 of 120,000 tokens at the end).

Tools that act ran for about 1,130 game seconds (57% of the budget) and waits for 806, and the game ran throughout both. Of the acting time, market_trade took 463 seconds, build_structure 189, set_workshop 178 (16 s a call), place_near 94 and expand_storage 72. From 15:07 its eight replies each ended in a wait of 60 to 150 seconds.

Providers and the prompt cache

Every request went to Anthropic's API with no provider routing. All 23 gameplay requests read the prompt cache, 96.7% of the input tokens (1,167,331 read, 39,347 written, 54 uncached). Of the $1.369 for play, output was $0.585, cache writes $0.492 and cache reads $0.292. The preparation request wrote 29,019 tokens ($0.455). The interview, 7 minutes 31 seconds after the last reply, wrote 69,546 tokens to the cache again (see For the harness).

The interview

Fable called its result poor: below leaving the game alone, under half the person's net worth, 45 people at popularity 50 against 250 at 100. It put the gap down to a low-yield chain (iron mines 60 tiles out and wood-fed workshops, against the person's bread from bought wheat in volume and 13 quarries), to food bought at 8 with the granary running dry twice, to the 24 idle peasants, and to the game time each market click took. Playing again it would open with a mill and as many bakeries as wood allows and buy wheat in one large purchase; build an inn at once on the starting ale, add a church and set rations off; put quarries and tethers on the western stone early; keep cheap buildings coming so idle peasants stay under 24; tax once popularity is held up; and trade in a few large lots. It found find_sites with tile targets, build_structure by tile, expand_storage, place_near and the stats useful, and asked for a per-click time estimate for market trades, a larger purchase per call, a "months of food left at this ration" figure, and a note that bread and flour volume chains pay at the sell prices.

Claims checked against the run:

• The granary did not run dry twice. Food was never below 18 until 32:46. Popularity's lows (42 at 22:31, 40 at 27:30) came on half rations (food −4) with 65 food in store.
• Popularity did not fall faster than the reading. The upcoming change read −3; it fell 17 in about 6 game months twice (76 to 59, 59 to 42), −2.8 and −2.9 a month.
• "~30 iron": the stock rose 34 (15 to 49), but the mines delivered about 83, since swords and armour took 49.
• "~1,300 gold on workshops": 1,500; the two blacksmith's cost 200 each. "~900 on wood" is right (900).
• "~113 weapons, ~2,300": the armory held 113 at 32:00, worth 2,581, including 12 suits of armour; 119 worth 2,737 at the end.
• Time per click: 3.4 to 4.7 seconds a click, not 5 to 10, and the 20-lot wood purchase took 67 seconds; the reply that held it (build, buy, tax, wait) ran 2:05. A reply of six set_workshop calls with a tax change and a purchase ran 2:49. Production ran during all of it.
• Matches: the mines 60 tiles from the stockpile (57 to 69 from the keep), meat at 8 (worth 4), the inn at 20 wood and 100 gold with 20 ale in hand, 24 idle peasants from 4:04, set_workshop failing twice on a hovel drawn over the pick (2 of 11), and bakeries at 10 wood.
• Not testable here: its wheat at 23 and the profit of a bread chain; this game never traded wheat. In GPT-6.1 Sol's desert game wheat was 23 to buy and 8 to sell.
• "Population never grew" holds from 12:00, when it reached 45 (2 at the start).

For the harness

• The map probe. Fable called map_overview once, in its first reply (0:01). Its output lists stone and iron with distances and says "Tree groves (woodcutters): none on this map", which is right for this map: the cactus patches that 1.5.0's probe counted as groves in the other 1.6.3 desert games are not in what it saw. It built no woodcutter and bought planks instead.
• The interview missed the prompt cache. The last gameplay reply ended at 14:47:34 UTC; the run ended at 14:48:59 (after the 80-second wait and the final overview), and the series log has the game saved and scored at 14:55:05, six minutes later with nothing logged between. The interview began at 14:55:05, 451 seconds after the last reply, past Anthropic's 5-minute cache life, so all 69,546 tokens were written again ($0.869 at $12.50 per million, against $0.017 read at $0.25) for $0.946. Fable's other three games had gaps of 130 seconds (Sinkhole 1.7.1, about $0.10), 270 (Oasis 1.5.1, $0.13) and 341 (Oasis 1.6.3, $0.96 and no cache read), so the line falls at the 5 minutes.
• No warning while food ran out. The host's food, popularity and gold warnings arrived in 1.7.0 (CHANGELOG); 1.6.3 gave only the stats. The 1.7.0 changelog names Opus's 1.6.3 game on this map, a wait with little food that ended at popularity 0, among the reasons for them. Whether the 1.7.0 rule would have fired at the 32:00 observation, which showed food 13, was not replayed.
• set_workshop could not reach a poleturner behind a hovel (13:49 by tile, 15:07 by pixel); the workshop was left on its default product.
• The first armory found no room by the keep (2:09, no_free_spot_in_view), so the wing waited for find_sites at 4:07; the blacksmith's stood without an armory from 2:40 to 4:43.
• It asked for a per-click time estimate for market_trade and a months-of-food figure.
• The 3 hovels at 6:48 were placed with the reader unavailable ("placement errors may be missing"); all three are in the final count.
• Fable's games were the first played with the host running on the game machine itself; that does not change what the game plays.
• The game saved correctly at the end ("claude fable 5-1 1-6-3 edc045", in this folder).