Claude Opus 5.5

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. The checker is the same model as the player.

• Model: Claude Opus 5.5 (claude-opus-5-5) on the Anthropic API, reasoning medium, output limit 32,768 tokens
• Benchmark: Oasis by the Sea construction (no arms), version 1.7.3 (commit b967c65), 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. Weapons and armour in store count nothing toward net worth; sold at a marketplace, they bring their gold.
• Run f95496e6, series 20261016T204131-27075351, 2026-10-16: Opus's no-arms game, a fresh series with no memory of its others. Its weapons-counted game on this version (run 5aa57408, series 20261016T201053-354922a4) was played earlier that day; its Oasis games from earlier rounds are run 4c18ab9b (1.6.3) and run a4c1769c (1.5.1). This game counts on the website's leaderboard.

Result

A full-budget score: the run used all 2,000 game seconds. Net worth grew by 6,320 over leaving the game alone, 34.5% of the person's 18,293, against 6,070 (33.2%) in the weapons game. By the website's formula (80% net worth share, 10% each population and popularity, the net-worth share clipped to −1..2) the score is 37.7: 27.64 points from net worth, 3.79 from 79 people and 6.30 from popularity 63. That is 4.8 above the weapons game and 14.3 under the 1.5.1 game. The stored goods are 184 iron (4,232), 217 stone (1,519), 258 wood, 18 wheat (144) and 6 apples (24); iron and stone are 76% of net worth, gold 18%. The town ended with 24 idle peasants and 27 free places in its hovels.

How the game went

Times are the game clock when a call began, read from the recording (the run clock quoted in observations reads 3 to 5 seconds later). A build call keeps the game running 0 to 105 seconds while it clicks; the game is paused while the model replies (under 2 game seconds passed in any of its 58 replies).

0 to 9 minutes. After map_overview and two find_sites it placed three woodcutters on the 42-tree grove the overview put 62 tiles from the keep, and an iron mine, in one call at 0:03 that ran 105 seconds. It saw the granary standing and never asked for one. Two hovels at 1:56, average taxes at 2:28. The marketplace costs 5 wood and it had 4 (2:47), so it waited; the woodcutters had delivered nothing by 3:17. At 3:56 there were 24 people in 26 places, 18 of them idle with no open job. Two orchards, a dairy farm and two woodcutters at 3:59; popularity fell from 98 (2:43) to 64 by 6:54, and taxes went to low at 6:56. Iron mines at 7:04 and 7:33, the marketplace at 8:27 and 40 planks (160 gold) at 8:45.

9 to 17 minutes. Two iron mines at 9:20 and two stockpile piles at 9:41 (4 to 12 piles); three hovels and a dairy farm at 10:23 (housing 58), no taxes at 11:15; two more iron mines at 11:59, two quarries at 12:44, two tethers at 13:19. A wheat farm at 11:31 found no room. At 15:27 a chapel was refused ("Too close to signpost to build.") while two hovels in the call stood (housing 74). At 16:38 the chapel went up at (398, 360) for 250 gold, with the eighth iron mine. The first stone reached the stockpile at 16:56, 3 min 46 s after the quarries were placed.

17 to 33 minutes. Quarries three to six and tethers three to five at 17:24, 19:54, 20:26 and 21:50, and a wheat farm on the tile refused at 11:31. At 22:29 a warning read 21 food for 74 people; it bought 25 bread and 20 meat. Average taxes at 23:50, four hovels at 24:11 (housing 106), and three woodcutters at 25:30, its last production buildings. After them: taxes to none at 27:05 (a warning: popularity 58 to 47), two stockpile piles at 28:27, 15 apples at 31:26, and waits of 40, 60, 60, 90 and 120 seconds. Wood rose from 104 (28:25) to 258.

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; wheat (144 at the end) is left out, so it reads slightly low, and the last column is the true net worth.

Weapons

It left them alone. It built no armory and no fletcher's, poleturner's, blacksmith's, armorer's or tanner's workshop, called no set_workshop, sold nothing, and held no weapon or armour at the end (no such line in the stored goods or the building list). None of its 92 tool calls touched them: its three building_info calls were for the Marketplace, the Apple Orchard and the Chapel. It wrote about weapons only in its opening reply, which restates the rule (weapons in the armory count nothing); none of its 50 logged reasoning blocks after that, nor its hand-off, mentions weapons, an armory or a workshop.

In its weapons-counted game it did build them: an armory and three fletcher's workshops at 16:39 and a fourth at 20:13, all set to crossbows, which made 15 crossbows worth 450. By the table in prompt/game-mechanics.md the workshops and armory cost 400 gold and 85 wood and the crossbows 45 wood: about 530 of gold and wood for 450 in the armory, roughly 80 of net worth (0.35 points) below building none. So weapons do not explain the 4.8-point gap between the two games, which splits into 1.09 points from net worth, 0.86 from population and 2.90 from popularity. Without its crossbows the weapons game had 6,840, 700 under this one, with 17 fewer people and 29 fewer popularity points.

Beside its other games and the other models

The 1.5.1 game is the only one with a bread chain: it bought 100 wheat for 2,300 gold, ran 13 bakeries and ended with 107 people, popularity 82, 184 bread and 2,471 gold, though its purchases cost 2,635 of net worth. Its rules said weapons add nothing and no tool offered the Armory, so it is the nearest to this game in rules, and this game scored 14.3 under it (10.99 points from net worth, 1.41 from population, 1.90 from popularity). So for Opus weapons do not account for the move from the 1.5.1 round: with none, a 1.7.3 game still stands 14.3 under. They may account for part of the gap to the other two: the 1.6.3 and 1.7.3 weapons games scored 28.9 and 32.9 against 37.7, and their workshops cost 1,400 and 400 gold. One game of each kind proves little.

Beside the other models. Among the 1.6.3 round's second games on this map, 37.7 would stand fifth of eleven, after Gemini 4 Argon (68.0), GPT-6.1 Sol (54.6), Fable (45.2) and Sonnet (44.9); against the first round it would be eighth, below Luna (39.0). Of the six 1.7.3 games played so far it is the highest score, and its net worth is second to Sonnet's 7,832 (240 of it in weapons). Haiku scored 23.0 with weapons and 26.9 without, Sonnet 36.5 and 31.4, Opus 32.9 and 37.7.

What held it back

• Wood, not gold, limited the first 9 minutes. At every observation from 1:53 to the first purchase (8:45) wood read 4 to 40 while gold read 1,000 to 1,258. The marketplace was first weighed at 2:47 and placed at 8:27; the weapons game placed its marketplace at 1:54 and bought 75 planks at 2:12. The run does not show that earlier buying would have paid: that game was lower at 6 minutes (1,110 against 1,468) and, without its crossbows, 700 lower at the end.
• Jobs ran out. From 15:26 no reading showed fewer than 18 idle peasants; 24, the cap at which new peasants stop arriving, read in 8 of 38 readings, and open jobs read 0 in 37. Searches came back empty for iron mines near (415, 340) at 17:24, orchards near (440, 395) at 21:40 and (400, 420) at 21:50, and a quarry near (385, 380) at 25:30; it searched for no iron mine after 17:24, though the 21:50 overview listed 116 ore tiles in four patches. Population stood at its 74 places from 22:20 until the hovels of 24:54.
• Food stayed thin. Apples and cheese from 4 orchards and 2 dairy farms, with 6 food at the end. Its opening plan said to add wheat farms with a mill and bakery, and an inn; no mill, bakery, inn or hops farm was built, and its logged reasoning names none (only an inn's ale chain, 15:27). The one wheat farm (done 22:29) made 18 wheat, never milled.
• A chapel that did nothing. 250 gold (1.1 points) for a religion factor that read 0 at every observation from 17:21 (+2 in Opus's 1.6.3 game and Sonnet's no-arms game); why is not in the logs.
• Almost nothing built in the last 7 minutes. From 26:13 it placed only two stockpile piles; 258 wood (a mine or quarry is 20 wood and no gold) and 1,363 gold ended unspent.

What worked

• Eight iron mines and six quarries. 184 iron (4,232, 56% of net worth, about 1 iron a minute a mine) and 217 stone (1,519, 10.7 a minute at 31:29 from six quarries and five tethers).
• Taxes and popularity. Popularity never went under 46. The one late average-tax stretch (23:50 to 27:05) took gold from 1,042 to 1,483 (+441, nothing bought meanwhile) at the cost of 16 popularity points and 7 people (79 to 72, popularity under 50 from 26:43 to 28:29); both recovered by the end. Taxes ran at average for about 7¾ minutes, low for 9½ and none for 16, and brought roughly 1,250 in all (end gold less the 1,000 start, plus 890 spent).
• Warnings answered. The drop at 27:03 was met with no taxes at 27:05. The food warning at 22:29 was met with bread and meat, and popularity rose from 52 to 63 by 23:56 (four foods eaten, food factor +3), fading as the stock ran out.
• Placements held. All 52 placements reported as placed are in the final count; four did not go through (an orchard 5:49, the wheat farm 11:31, the chapel 15:27, a quarry 20:26). One call was refused (9:12, below) and no model request failed.

Market

40 planks (4 each, worth 1; 8:45), 25 bread and 20 meat (8 each, worth 4; 22:30 and 22:54) and 15 apples (31:26) bought for 640 gold; nothing sold. The purchases lost 360 of net worth against the sell price (planks 120, bread 100, meat 80, apples 60), 4.8% of the final; selling leaves net worth unchanged. These are units at the market's fixed prices. The four market calls took 89 game seconds.

Cost and speed

58 turns, 92 tool calls (28 find_sites, 22 build_structure, 16 waits, 9 set_tax, 4 market_trade, 13 others), 3.14 million tokens and $1.491 at the profile's prices ($4 per million input, $20 output, $0.20 cache read, $5 cache write): preparation $0.164, play $1.274, compaction $0.054. The interview, which began 43 s after the run ended, cost about $0.044, with 62,684 of its 65,259 tokens read from the cache. The agent run took 29.3 real minutes, 4.9 of them waiting for the model; the context was compacted once, at 16:34 (16 s). All 58 requests read the prompt cache, 97.5% of the input tokens, with no provider routing. Of the 2,000 game seconds the 22 build calls took 806 (40%), the 16 waits 723, set_tax 84 (about 9 s a call) and the host's 5-second top-up after 18 actions made without a screenshot 90. The weapons game cost $1.135 with 40 turns.

The interview

Opus put the person's net worth at about 2.6 times its own and named three causes: no processing chain (the person's 57 bakeries; it built no mill or bakery and treated wheat as stock), the 24-idle-peasant cap, and popularity (tax swings, food nearly out, food bought at a loss, no fear buildings). Playing again it would build wheat, mills and bakeries early, make jobs before the cap, place a church early and away from the signpost, try cheap bad things and cut time lost to camera moves. It praised find_sites, tile-targeted building and the stats JSON; it disliked the game-time cost of off-screen placements and the 5-second top-up, detail lost in compaction, and no way to tell a stalled producer, and asked for a game-seconds estimate for camera moves and for marketplace auto-buy and auto-sell. Its biggest mistake, it said, was strategic: raw stockpiles count directly, and it missed that population, popularity and a processing chain compound.

Against the game these match: 2.6 times (7,540 against 19,513); stone, iron and wood are 80% of net worth; no mill or bakery; idle never under 18 from 15:26; nine set_tax calls between levels 3 and 5; food bought at a loss; the first chapel refused at the signpost (15:27); build calls up to 105 s; stone standing flat while the production window showed deliveries (below). These do not match or cannot be checked. The top-up is not "after each action reply": it followed 18 replies that acted without a screenshot. Its case for a church is not shown by its own game: the chapel it built read religion 0 throughout, so the +3 rests on the person's. One of its four purchases was planks, not food. "Couldn't find new jobs fast enough" holds for three empty searches, but it made none after 25:30. It never traded wheat, so buying it, as the person did, is untested. What compaction lost is not in the logs. No tool sets auto-buy or auto-sell (market_trade trades by hand, though prompt/game-mechanics.md describes the game's thresholds); its weapons game and its 1.5.1 interview asked for the same.

For the harness

• The granary line. The rules' Start paragraph still tells the model to place a granary; the save has one. No call was rejected here: its first reasoning saw it standing.
• A listed spot the game refused. find_sites gave (451, 363) as a chapel site at 15:27 and the game refused it as too close to the signpost; the remedy points back to find_sites. A hovel in that call carried the same message but is in the final count.
• One refused call. At 9:12 a build_structure with pixel targets, sent in the same reply as a market_trade, was refused (no screenshot after the trade); the model re-sent it with tile targets at 9:20 and both mines went up.
• The same wheat-farm tile (431, 395) was not_placed with no_open_side at 11:31 and placed at 21:50; nothing in the logs says what changed.
• Stone in lumps. The production window shows 16 to 48 stone delivered per 3 minutes while the count stood still for 155 s from 17:11, 132 s from 20:30 and 112 s from 28:26; at 19:02 the model wondered what was draining wood and stone, and at 29:44 whether the oxen had stopped.
• At about 5:48 the game's garbage collector stalled for 20 seconds and the reader forced a collection (the run's only one); the recording shows a 10-second gap in frames and the run went on.
• The game saved correctly at the end ("claude opus 5-5 1-7-3 f95496").