Amarna Letters

A strategy game with no diplomacy rules, set among the seven Great Kings of the Late Bronze Age (c. 1360–1330 BCE) and the city-states between them. The engine enforces physics: movement, combat, production and payment. Every treaty, alliance and betrayal is invented by the players. Kings never speak to each other directly: every word travels with an envoy who has motives of their own.

This is the prototype described in the design document Amarna Letters — Prototype Design Document. Its job is to test one hypothesis: if communication is delayed, mediated by people with their own motives, and impossible to verify fully, then norms of trust, reputation and enforcement emerge on their own.

Play it in your browser: https://haaktuah.github.io/amarna-letters/

Play a king or a city yourself, watch Claude play them all, or mix the two. With no API key, every king and envoy is a script player, and a whole game costs nothing.

The message trail. Every message exists in three versions: what the king wrote, what the envoy said at the foreign court, and what the envoy reported home. The gaps between them are the game.

How to play

You are one of thirty powers: the seven Great Kings, Egypt, Hatti, Babylonia, Mitanni, Assyria, Arzawa and Alashiya, or one of the city-states and chiefs between them, Byblos, Amurru, Ugarit and the rest, on one scoreboard: each power is judged by its growth against par for its starting position, so a city that holds its own can win as well as an empire. Each season you read what reached your court, receive foreign envoys, and give your orders in secret. Every king orders at the same time, and the engine resolves everything at once. Three seasons make a year.

You see only what your kingdom can see: your own land, the provinces where your troops stand or your spies watch, and one step beyond them. Everything else you know from letters, reports and rumours, and those can be late, shaded or false.

A season

1. Income and upkeep. Provinces pay gold. Troops, servants and raised walls are paid. Troops the treasury cannot pay desert; unpaid servants are owed back pay, and remember it.
2. Arrivals. Envoys, gold, spy reports and rumours that were on the road arrive.
3. Audiences. Foreign envoys deliver their message in their own words. The host answers, and may bribe the envoy, offer it a post, seal its tablet, detain it or send gold back. Each audience has up to two exchanges, and the envoy decides how to respond.
4. Orders. Every king submits secret, simultaneous orders.
5. Resolution. Movement and battles, then sieges. Land changes hands, and a kingdom whose capital is taken falls. Then come cessions and gifts, purchases, walls, levies, envoys setting out, hiring, intelligence and seeded catastrophes.
6. Reports. News of the season reaches each court the next season.

What a king can do

Armies and fleets.

• Move, hold, support and convoy, as in Diplomacy. Strength is one plus supports, ties bounce, and there are no dice. You may support any power's unit, which is how alliances fight together.
• Besiege a walled city your army stands in, or sally from your own walls (level 2 or more) against troops inside them.
• Give standing orders that answer a blow in the same season, while you sleep or play.
• Raise an army (100 shekels) or a fleet (120) in an empty province of your homeland, or disband one. Upkeep is 30 a season for an army and 35 for a fleet.

Land and gold.

• Take a city by conquest, or as your vassal by a sealed tablet: no city is bought.
• Cede provinces, give troops, and send gold with an envoy.
• Debase the gold you send. The receiver's ledger counts it at face value until they pay 10 shekels to assay the lot.
• Strengthen the walls of a city you hold, up to level 3, for 50 shekels times the new level.

Envoys and letters.

• Send up to three envoys a season, each with a letter of up to 1,500 characters, a mandate saying what it may agree to, gold, and tablets. An envoy takes one to three seasons each way, by distance.
• Every letter opens with the formula of the real Amarna letters ("Say to …, my brother: thus says the Great King …"). Who is called brother, and who is granted "Great King", shows how a court stands with you.

Tablets.

• Write a treaty on a tablet (20 shekels) for your envoy to offer for sealing.
• Send a copy of a sealed tablet to a third court as evidence.
• Have a tablet examined for forgery, or forge one yourself (40 shekels, with a servant skilled enough).
• Tablets are evidence only: nothing in the engine enforces them.

Court and spies.

• Hire from the open market, where people name their own price, and dismiss servants.
• Run background checks on what a person hides.
• Post spies at a foreign court or in a province, and pay watchmen against other kings' spies.
• Hold a caught spy for ransom or try to turn it, and pay the ransom for one of your own.

Walls, sieges and terrain

Every capital has walls of level 3. The great fortresses (Carchemish, Qadesh, Tyre, Megiddo, Gaza, Mari, Susa, Memphis, Kanesh and Nineveh) have 2, and a few walled towns have 1.

• Storming. Walls add nothing to a field battle. A move into a walled city takes it at once only if its strength also beats the walls plus the defenders.
• Besieging. Otherwise the army stands inside and can besiege. Each season it holds there wears the walls down a step, or two with a support. A besieged city yields nothing, and the siege costs the besieger 15 shekels a season.
• Envoys under siege. An envoy leaving a besieged capital may be caught, and a timid one will not go.
• Terrain. A unit standing its ground on rough ground, behind a mountain pass or a great river, or against a landing from the sea, gets +1. An army in desert land its king did not hold pays 30 shekels a season for supplies.

Winning

A king's strength is ten times the yield of the land he holds, plus his gold, minus back pay he owes. Conquered land counts as it is absorbed: a third in its first season, two thirds in the second, all of it from the third. The winner is whoever grew most relative to their own start.

Any season may be the last, from the first: early on it is very unlikely, and it grows likelier with every year, so that half of all ages have ended by 1332 BCE (season 44). The engine draws the last season once, in secret, at the start, with a hard cap drawn from 80 to 100 seasons; nothing shown reads it. The median and the cap's range (or none) are table settings, and a table can play an open age with no end, from the start or by playing on once the age has ended.

A kingdom falls with its capital: its remaining land passes to the conqueror, and its troops disband. A fallen player watches the rest of the game in god view (a table setting).

There is one winner. Shared victory for sworn allies is a house rule, off by default.

The seven Great Kings

Every king reads every power's opening position. The script kings each play a temperament of their own, varied a little in every game.

Power	Capital	Tier	Starts with	How the script king plays
Egypt	Akhetaten	Strong	armies in Memphis and Akhetaten, a fleet in the Nile Delta, 600 shekels	"Pharaoh of the gilded gifts": generous, proud and diplomatic; buys friends with gold "as plentiful as dust"
Hatti	Hattusa	Strong	armies in Hattusa and Kanesh, a fleet in Kizzuwatna, 300 shekels	"The conqueror of Anatolia": the most aggressive king, vengeful, little given to trade
Babylonia	Babylon	Strong	armies in Babylon, Sippar and Dur-Kurigalzu, 650 shekels	"Keeper of the old order": the proudest and greediest; cautious, and will not call Assyria brother unless they are friends
Mitanni	Washukanni	Middle	armies in Washukanni, Taidu and Terqa, 500 shekels	"Seeker of a patron": the most diplomatic and among the most honest; squeezed between Hatti and Assyria
Assyria	Ashur	Middle	armies in Ashur, Nineveh and Ekallatum, 350 shekels	"The upstart who would be brother": aggressive and cunning, hungry to be counted a Great King
Arzawa	Apasa	Weak	armies in Mira and Apasa, a fleet in Seha, 300 shekels	"The western opportunist": the most cunning and least honest
Alashiya	Enkomi	Weak	a fleet in Enkomi, 350 shekels	"The copper merchant": the island trader, the most cautious and least aggressive

Between the great kingdoms lie the city-states, such as Ugarit, Byblos, Qadesh and Elam, and the Kaska, Lukka and Sutean chiefs: twenty-three powers of their own, most of them vassals of Egypt or Mitanni by sealed tablets, with the same rules and the same goal as the kings. Alashiya is an island, reached only by sea.

A script king sees only what its seat sees. It remembers who wronged it and who kept faith, and checks its orders against what its rivals are likely to do by playing the season out with the engine's own adjudicator. When one king runs away with the game, the others swear coalitions against him and strike at his land together; a king attacked by a strong neighbour asks the neighbour's other neighbours for a defence pact. Script kings give standing orders too. The god view lists each king's temperament under Standings. Every rule they follow, with its numbers, is in docs/DESIGN-NOTES.md under "Script kings".

The courts

No court has missions, goals or rules of its own. Each plays differently because of what it has, what it lacks and where it stands, and the same court plays differently from game to game as floods fail, roads close and rivals change. This is the picture the game is growing towards; for now, position and relations do most of the work.

• Egypt, the banker. Rich in gold and grain, short of horses, timber and tin. Its game is spending well: buying allies, horses and cedar, and holding Canaan to keep the coast road.
• Hatti, the soldier with an empty granary. Horses and silver, rain-fed land that fails in drought, and enemies on every side. It needs wars that end quickly, and grain from Syria or Egypt.
• Mitanni, the toll keeper in a vice. Horses, and the Euphrates crossing that eastern tin takes going west, squeezed between Hatti and a rising Assyria. It collapsed in exactly these years, so its game is survival.
• Babylonia, the distant merchant prince. Grain, horses and the start of the eastern tin road, far from the fighting. Its game is prestige, recognition and marriages, and it can tighten the tin.
• Assyria, the upstart. Small, on the tin road, growing by squeezing Mitanni and fighting to be counted a Great King. Burna-Buriash of Babylon protested to Pharaoh at Assyrians being received as if they were independent (letter EA 9).
• Arzawa, the western sea power. River gold, and a coast where western tin lands; Hatti's rival from the other side.
• Alashiya, the lottery winner. Copper and timber of its own on its island. Its game is price and balance, and tin is its weak point.

The Levant, the boiling pot. Between the great kingdoms lies the board's centre: a crowd of vassal cities where the spheres of Egypt, Mitanni and Hatti meet. Each ruler protests his loyalty to Pharaoh while taking his neighbours' towns and denouncing them as traitors, and most of the surviving letters are theirs. Rib-Hadda of Byblos wrote more than sixty, begging for troops and grain against Abdi-Ashirta of Amurru and then his son Aziru, who played Egypt against Hatti and in the end went over to Hatti. It is where the great kings' spheres meet, and where the truth is hardest to find.

Envoys and other servants

Eighteen people move between the courts: eight with names attested in the Amarna letters (Mane, Keliya, Pirissi and others, seven drawn each game) and the rest named in their region's style. Each power starts with two envoys; the rest are free agents, looking for a master.

Each has traits from 0 to 100 (loyalty, greed, competence, ambition, courage, and sympathy for a court), secrets at three levels of secrecy, and a memory that travels with them to a new master. Nobody shows you their traits. You learn them from what they do, from background checks, and from what others tell you.

What an envoy can do to your words, and why:

• Soften them. A timid envoy, or one fond of the host, drops the threats aimed at the host.
• Shade the report home. A faithful one repeats the host word for word. A bribed one, or a timid one that is not faithful, leaves out the host's threats against you.
• Sell them. An envoy that took a host's gift carries home what the host asked it to say, and vouches for it.
• Overreach. An ambitious envoy may promise more than its mandate, then tell you it gave "such assurances as you would wish".
• Skim. A greedy, disloyal envoy keeps part of the gold it carries, and may forge a new inventory to hide it.
• Change masters. An envoy takes a host's offer of a post if it pays well enough and its loyalty is low, or if it already favours that court.
• Be detained. A host may hold your envoy, and with it your letters and gold.

Servants are paid every season. One left unpaid loses loyalty and is owed back pay, and may give notice. When a contract ends, the servant names a price to stay.

Spies watch a court or a province and send reports home. Watchmen catch them, and a caught spy can be ransomed, or turned into a double agent who sends home poisoned reports.

Envoys are script characters in the Free and Local agents presets and Claude Haiku in the others; Customize can give them Sonnet.

Playing with Claude

Pick a preset, choose whether to watch or take a seat, and begin.

Preset	Kings	Envoys and spies	Narrator	Rough cost per 20-season game
Free	Script kings	Script	Template	$0, no key needed
Budget	Haiku 5.5	Haiku 5.5	Haiku 5.5	under $1
Standard	Sonnet 5.5	Haiku 5.5	Sonnet 5.5	about $9
Showcase	Opus 5.5	Haiku 5.5	Opus 5.5	about $20
Local agents (this computer only)	Claude Code agents	Script	Template	your Claude subscription, no key

Envoys stay on Haiku even in Showcase: they make the most calls, and the design wants fallible messengers. Customize the table sets each king separately (script, human, Haiku, Sonnet or Opus, for model-against-model experiments, and a local agent when the app runs on your computer), Sonnet envoys, the narrator, thinking effort and the house rules. The estimates are rough; the meter in the game shows the real spend, and the game pauses at a spending cap set from the estimate (you can change it).

Model seats use your own Anthropic API key: calls go straight from the page to the Anthropic API, and the key is never stored outside this tab. Use a dedicated key with a spend limit set in the Anthropic Console. Simulate the API (under Customize) tries model seats with canned replies; nothing leaves the browser. When a model call fails, a script king or character makes that decision instead, the failure is listed at the top of the side panel, and the game goes on.

Local agents is local play, for your own games: you take a seat, and the other kings are guarded Claude Code agents answered in a Claude Code session on your Claude subscription, through a small bridge on this computer (node sim/bridge.js). It appears only when the app runs on your computer. The steps are under "Local play" in sim/README.md, and the session's start prompt is docs/PLAY-PROMPT.md.

Sleeping seats

Long games become affordable when model calls scale with events, not with time. Sleeping seats are on by default: after giving its orders, a model king sleeps, and it never chooses when it wakes. The world goes on, its units hold and its scheduled orders run, each following its unit (a march stopped by a bounce tries the step again, and a new levy can be given orders ahead), and its standing orders answer, in the same season, a unit it sees setting out to enter a province or to attack one of its own. It is woken only when something concerns it: an envoy at the door, foreign troops in its land or arriving next to its homeland or a walled city it holds, land or troops lost, a failed scheduled or standing order, a servant giving notice, or a ransom demanded. Everything else waits in a digest, and a hidden safety cap wakes it after a long sleep. Script and human kings play every season. Switch it off (Customize in the web app, --sleep off in the batch runner) to ask every king every season. Standing orders are every king's, awake or asleep: script kings give them, and a human gives them in the orders panel. The details are in docs/DESIGN-NOTES.md.

Watching a game

In games without a human, the god view shows everything the engine knows: true map, every treasury, every character's hidden traits and facts and who knows them, and the message trail: for every message, what the king wrote, what the envoy said abroad, and what the envoy reported home. Switch to any power to see exactly what it saw. The side panel's tabs show the season's events, the trail, the people, the provinces, the standings and the rules. The timeline steps back through the seasons; signals mark sealed tablets, accusations, forgeries, broken promises and more. After the game, compare two nations' self-serving annals with the true record.

The map is a museum map of the Late Bronze Age: coasts, rivers, mountains, deserts and fields, each power in its colour with an emblem and a border line of its own (so it reads without colour), armies as chariots and fleets as ships. Step the timeline and each season's moves, attacks, supports, bounces and captures are drawn; envoys, spies and gold appear on the road and at foreign courts. In a power's view the fog of war fades with the age of its sight, and uncertain things (old sightings, rumours, spy reports) are drawn as such. Tap anyone to follow their life: their path, their masters, their missions, what they said and reported.

A link to play?watch=7 (any seed) starts a game of script kings to watch. Games are saved in the browser, and a game's log can be exported and loaded again to replay it exactly.

On a phone

It is built phone first: the map fits the screen with pinch-zoom, the panels open from it, and the app installs to the home screen and starts from cache.

Your first live game: a checklist

1. Create a dedicated API key with a low spend limit (a few dollars) in the Anthropic Console.
2. Start with a mixed table: Sonnet 5.5 leaders, script characters, template narrator. Set the budget to $3.
3. Watch the cost meter in the game's header for the first two seasons; the per-season figure tells you what a full game will cost.
4. Open the Message trail tab once envoys start arriving: the gap between what was written, said and reported is the thing to look at.
5. If calls fail, the top of the side panel lists them; each failed call falls back to a script decision and the game continues. Export the log (the ⋯ menu) to keep the prompts and outputs.

For developers

Run locally

You need Node 22 or later.

npm ci
npm run dev --workspace src/web

Then open http://localhost:5183, pick a preset, choose whether to watch or take a seat, and begin.

Tests and the batch runner

scripts/test.sh          # type-check, the engine's determinism lint, and every test (Vitest)

scripts/sim.sh --games 50 --seed 1 --verify-replay

The batch runner plays games unattended and prints wins by power and the success signals. With ANTHROPIC_API_KEY set it can run model games too (--preset budget, or per role: --leaders sonnet --characters haiku --narrator sonnet), stopping at --budget dollars; every such game costs real money. --no-primer runs the customs-primer experiment; --out logs keeps every game's log. --versus solo measures the script king against the frozen first version (one king at a time, against six of the old), and --versus baseline and --focus <Power> mix the two. Script games run on every core. --sleeping-scripts lets script kings sleep as model kings do; they then schedule conditional orders ahead, which --no-plan-ahead turns off and --plan-ahead-half gives to half of them, to measure what it is worth. The measure of call size (item 6b) shadows script games with model kings and splits their requests into parts: node --experimental-strip-types --no-warnings src/batch/src/measure.ts --games 20 --seed 1 (--per-audience for one call per audience, --dump DIR for sample requests). It calls no model. --sleep off turns off sleeping seats, --sleep-cap N sets the hidden safety cap on a sleep, --max-turns N stops a game after season N at the latest (a known cap), --cap 80-100 or --cap none sets the hard cap's range, and --median N the season by which half of all ages have ended (44 by default). --file-seats DIR makes every king a file seat: it writes what a model king would see to its own folder and waits for a JSON reply file, which is how sim/ plays a game with Claude Code agents as the kings (see sim/README.md).

Publishing and CI

Changes go in through pull requests: every pull request builds and runs the tests (.github/workflows/pages.yml) and gets a playable preview at its own address, https://haaktuah.github.io/amarna-letters/pr-<number>/, linked in a comment on the pull request and removed when it closes (.github/workflows/preview.yml). Merging into main publishes the browser game at the site's root. Both are written to the gh-pages branch, which Pages serves: main to its root, each pull request to its own pr-<number>/ folder (scripts/site-prepare.sh, scripts/site-publish.sh). No pull request's own code can write to that branch, so none can replace the root. To publish the static files somewhere else, such as S3:

npm run build --workspace src/web

The site is src/web/dist. If it is served from a sub-path, set <base href> in its index.html to that path.

How it is put together

Every game is deterministic: the same seed and the same decisions give the same game, and every log replays exactly.

Package	What it is
src/engine	The deterministic engine: map, state, orders, validator, adjudicator, economy, envoys, tablets, spies, catastrophes, scoring. Pure TypeScript, no I/O; a lint config keeps out clocks, unseeded randomness, culture-sensitive text and inexact Math.
src/game	Seats, character minds and the narrator as interfaces; the runner that records every decision; script kings (temperaments, memory, a look-ahead over likely rival orders) and script characters; signal detection.
src/llm	Claude leaders (Sonnet 5.5 / Opus 5.5), characters (Haiku 5.5) and narrator (Sonnet 5.5): prompts, JSON schemas, parsing, cost accounting, the API simulator, file seats and the local bridge. Calls are posted with fetch, in the browser and the batch runner alike.
src/web	Vite and React app: setup, SVG map, human orders and audiences, spectator views, timeline, chronicles, IndexedDB saves. The engine, the script kings and characters run in a Web Worker; the page only shows what it sends.
src/batch	Node runner for unattended games, on worker threads.
src/*/test	The tests (Vitest), ported from the C# suite: engine, script kings and characters, model layer against a simulated API, and the web map's scenes.
tests/fixtures	Recorded model games (JSON lines), kept as data. The C# build the game was converted from (build order item 5+) was removed after the fix pass; it is kept on the branch archive/csharp-final (commit 5b4caa2).

Design notes

docs/DESIGN-NOTES.md records every decision and simplification made while building, and every rule as implemented. docs/BUILD-PROGRESS.md tracks the build order item by item, with each item's report in docs/rounds/.

Credits

The game was inspired by Irving Finkel's Curator's Corner episode 100, "Reading the Pharaoh's private mail with Irving Finkel" (The British Museum, https://www.youtube.com/watch?v=3MZq_ZQDhJA), and leans on William L. Moran's The Amarna Letters for the translations of the letters themselves.