diff --git a/docker-compose.yaml b/docker-compose.yaml
index 535040a..1a92bb1 100644
--- a/docker-compose.yaml
+++ b/docker-compose.yaml
@@ -2,6 +2,6 @@ services:
   server:
     build:
       context: .
-      dockerfile: packages/example-server/Dockerfile
+      dockerfile: packages/wonders-server/Dockerfile
     ports:
       - "4000:80"
diff --git a/packages/wonders-common/.eslintrc.json b/packages/wonders-common/.eslintrc.json
new file mode 100644
index 0000000..7e12a23
--- /dev/null
+++ b/packages/wonders-common/.eslintrc.json
@@ -0,0 +1,24 @@
+{
+    "env": {
+        "es2021": true,
+        "node": true,
+        "browser": true
+    },
+    "extends": [
+        "standard"
+    ],
+    "parser": "@typescript-eslint/parser",
+    "parserOptions": {
+        "ecmaVersion": 12,
+        "sourceType": "module"
+    },
+    "plugins": [
+        "@typescript-eslint"
+    ],
+    "rules": {
+      "comma-dangle": ["error", "only-multiline"],
+      "padded-blocks": "warn",
+      "no-multiple-empty-lines": "warn",
+      "space-before-function-paren": "off"
+    }
+}
diff --git a/packages/wonders-common/index.ts b/packages/wonders-common/index.ts
new file mode 100644
index 0000000..3cd08e8
--- /dev/null
+++ b/packages/wonders-common/index.ts
@@ -0,0 +1,428 @@
+import min from 'lodash/min'
+import chunk from 'lodash/chunk'
+import isInteger from 'lodash/isInteger'
+import sampleSize from 'lodash/sampleSize'
+import shuffle from 'lodash/shuffle'
+import sum from 'lodash/sum'
+import max from 'lodash/max'
+import head from 'lodash/head'
+import tail from 'lodash/tail'
+
+export const minAge = 1
+export const maxAge = 3
+export const minPlayers = 3
+export const maxPlayers = 7
+export const startingGold = 3
+export const discardGold = 3
+export const victoryPoints = [1, 3, 5]
+export const defeatPoints = -1
+export const goldPerPoint = 3
+export const scienceSetPoints = 7
+
+type Resource = 'wood' | 'stone' | 'ore' | 'brick' | 'paper' | 'cloth' | 'glass'
+type Science = 'engineering' | 'research' | 'education'
+type StructureType = 'commerce' | 'culture' | 'science' | 'basic industry' | 'advanced industry' | 'guild' | 'military'
+type Countable = StructureType | 'wonder stage' | 'defeat'
+
+export interface Structure {
+  type: StructureType
+  name: string
+  appears?: (undefined | (3 | 4 | 5 | 6 | 7)[])[]
+
+  cost?: Map<Resource | 'gold', number>
+  freeWith?: string[]
+  paysFor?: string[]
+
+  gold?: number
+  goldPer?: Map<Countable, number>
+  goldPerNeighbor?: Map<Countable, number>
+  points?: number
+  pointsPer?: Map<Countable, number>
+  pointsPerNeighbor?: Map<Countable, number>
+  sciences?: Set<Science>
+  resources?: Map<Resource, number>
+  shields?: number
+  discountTrade?: {
+    resourceType: 'basic' | 'advanced'
+    direction: ('left' | 'right')[]
+    amount: number
+  }[]
+}
+
+const structuresAge1: Structure[] = [
+  { type: 'advanced industry', name: 'Glassworks', appears: [[3, 6], [3, 5]], resources: new Map([['glass', 1]]) },
+  { type: 'advanced industry', name: 'Loom', appears: [[3, 6], [3, 5]], resources: new Map([['cloth', 1]]) },
+  { type: 'advanced industry', name: 'Press', appears: [[3, 6], [3, 5]], resources: new Map([['paper', 1]]) },
+  { type: 'basic industry', name: 'Clay Pit', appears: [[3]], cost: new Map([['gold', 1]]), resources: new Map([['brick', 1], ['ore', 1]]) },
+  { type: 'basic industry', name: 'Clay Pool', appears: [[3, 5]], resources: new Map([['brick', 1]]) },
+  { type: 'basic industry', name: 'Excavation', appears: [[4]], cost: new Map([['gold', 1]]), resources: new Map([['stone', 1], ['brick', 1]]) },
+  { type: 'basic industry', name: 'Forest Cave', appears: [[5]], cost: new Map([['gold', 1]]), resources: new Map([['wood', 1], ['ore', 1]]) },
+  { type: 'basic industry', name: 'Lumber Yard', appears: [[3, 4]], resources: new Map([['wood', 1]]) },
+  { type: 'basic industry', name: 'Mine', appears: [[6]], cost: new Map([['gold', 1]]), resources: new Map([['stone', 1], ['ore', 1]]) },
+  { type: 'basic industry', name: 'Ore Vein', appears: [[3, 4]], resources: new Map([['ore', 1]]) },
+  { type: 'basic industry', name: 'Stone Pit', appears: [[3, 5]], resources: new Map([['stone', 1]]) },
+  { type: 'basic industry', name: 'Timber Yard', appears: [[3]], cost: new Map([['gold', 1]]), resources: new Map([['stone', 1], ['wood', 1]]) },
+  { type: 'basic industry', name: 'Tree Farm', appears: [[6]], cost: new Map([['gold', 1]]), resources: new Map([['wood', 1], ['brick', 1]]) },
+  { type: 'commerce', name: 'East Trading Post', appears: [[3, 7]], discountTrade: [{ resourceType: 'basic', direction: ['right'], amount: 1 }] },
+  { type: 'commerce', name: 'Marketplace', appears: [[3, 6]], discountTrade: [{ resourceType: 'advanced', direction: ['left', 'right'], amount: 1 }] },
+  { type: 'commerce', name: 'Tavern', appears: [[4, 5, 7]], gold: 5 },
+  { type: 'commerce', name: 'West Trading Post', appears: [[3, 7]], discountTrade: [{ resourceType: 'basic', direction: ['left'], amount: 1 }] },
+  { type: 'culture', name: 'Altar', appears: [[3, 5]], points: 2 },
+  { type: 'culture', name: 'Baths', appears: [[3, 7]], cost: new Map([['stone', 1]]), points: 3 },
+  { type: 'culture', name: 'Pawnshop', appears: [[4, 7]], points: 3 },
+  { type: 'culture', name: 'Theater', appears: [[3, 6]], points: 2 },
+  { type: 'military', name: 'Barracks', appears: [[3, 5]], cost: new Map([['ore', 1]]), shields: 1 },
+  { type: 'military', name: 'Guard Tower', appears: [[3, 4]], cost: new Map([['brick', 1]]), shields: 1 },
+  { type: 'military', name: 'Stockade', appears: [[3, 7]], cost: new Map([['wood', 1]]), shields: 1 },
+  { type: 'science', name: 'Apothecary', appears: [[3, 5]], cost: new Map([['cloth', 1]]), sciences: new Set(['research']) },
+  { type: 'science', name: 'Scriptorium', appears: [[3, 4]], cost: new Map([['glass', 1]]), sciences: new Set(['education']) },
+  { type: 'science', name: 'Workshop', appears: [[3, 7]], cost: new Map([['glass', 1]]), sciences: new Set(['engineering']) },
+]
+const structuresAge2: Structure[] = [
+  { type: 'basic industry', name: 'Brickyard', appears: [, [3, 4]], cost: new Map([['gold', 1]]), resources: new Map([['ore', 2]]) },
+  { type: 'basic industry', name: 'Foundry', appears: [, [3, 4]], cost: new Map([['gold', 1]]), resources: new Map([['ore', 2]]) },
+  { type: 'basic industry', name: 'Sawmill', appears: [, [3, 4]], cost: new Map([['gold', 1]]), resources: new Map([['wood', 2]]) },
+  { type: 'basic industry', name: 'Quarry', appears: [, [3, 4]], cost: new Map([['gold', 1]]), resources: new Map([['stone', 2]]) },
+  { type: 'commerce', name: 'Bazar', appears: [, [4, 7]], goldPer: new Map([['advanced industry', 2]]), goldPerNeighbor: new Map([['advanced industry', 2]]) },
+  { type: 'commerce', name: 'Caravansery', appears: [, [3, 5, 6]], cost: new Map([['wood', 2]]), freeWith: ['Marketplace'], resources: new Map([['wood', 1], ['stone', 1], ['ore', 1], ['brick', 1]]) },
+  { type: 'commerce', name: 'Forum', appears: [, [3, 6, 7]], cost: new Map([['brick', 2]]), freeWith: ['East Trading Post', 'West Trading Post'], resources: new Map([['glass', 1], ['cloth', 1], ['paper', 1]]) },
+  { type: 'commerce', name: 'Vineyard', appears: [, [3, 6]], goldPer: new Map([['basic industry', 1]]), goldPerNeighbor: new Map([['basic industry', 1]]) },
+  { type: 'culture', name: 'Aqueduct', appears: [, [3, 7]], cost: new Map([['stone', 3]]), freeWith: ['Baths'], points: 5 },
+  { type: 'culture', name: 'Courthouse', appears: [, [3, 5]], cost: new Map([['brick', 2], ['cloth', 1]]), freeWith: ['Scriptorium'], points: 4 },
+  { type: 'culture', name: 'Statue', appears: [, [3, 7]], cost: new Map([['ore', 2], ['wood', 1]]), freeWith: ['Theater'], points: 4 },
+  { type: 'culture', name: 'Temple', appears: [, [3, 6]], cost: new Map([['brick', 1], ['wood', 1], ['glass', 1]]), freeWith: ['Altar'], points: 3 },
+  { type: 'military', name: 'Archery Range', appears: [, [3, 6]], cost: new Map([['wood', 2], ['ore', 1]]), freeWith: ['Workshop'], shields: 2 },
+  { type: 'military', name: 'Stables', appears: [, [3, 5]], cost: new Map([['wood', 1], ['ore', 1], ['brick', 1]]), freeWith: ['Apothecary'], shields: 2 },
+  { type: 'military', name: 'Training Ground', appears: [, [4, 6, 7]], cost: new Map([['ore', 2], ['wood', 1]]), shields: 2 },
+  { type: 'military', name: 'Walls', appears: [, [3, 7]], cost: new Map([['stone', 3]]), shields: 2 },
+  { type: 'science', name: 'Dispensary', appears: [, [3, 4]], cost: new Map([['glass', 1], ['ore', 2]]), freeWith: ['Apothecary'], sciences: new Set(['research']) },
+  { type: 'science', name: 'Laboratory', appears: [, [3, 5]], cost: new Map([['paper', 1], ['brick', 2]]), freeWith: ['Workshop'], sciences: new Set(['engineering']) },
+  { type: 'science', name: 'Libary', appears: [, [3, 6]], cost: new Map([['cloth', 1], ['stone', 2]]), freeWith: ['Scriptorium'], sciences: new Set(['education']) },
+  { type: 'science', name: 'School', appears: [, [3, 7]], cost: new Map([['paper', 1], ['wood', 1]]), sciences: new Set(['education']) },
+]
+const structuresAge3: Structure[] = [
+  { type: 'commerce', name: 'Arena', appears: [, , [3, 3, 5, 7]], cost: new Map([['stone', 2], ['ore', 1]]), freeWith: ['Dispensary'], goldPer: new Map([['wonder stage', 3]]), pointsPer: new Map([['wonder stage', 1]]) },
+  { type: 'commerce', name: 'Chamber of Commerce', appears: [, , [4, 6]], cost: new Map([['brick', 2], ['paper', 1]]), goldPer: new Map([['advanced industry', 2]]), pointsPer: new Map([['advanced industry', 2]]) },
+  { type: 'commerce', name: 'Haven', appears: [, , [4]], cost: new Map([['wood', 1], ['ore', 1], ['paper', 1]]), goldPer: new Map([['basic industry', 1]]), pointsPer: new Map([['basic industry', 1]]) },
+  { type: 'commerce', name: 'Lighthouse', appears: [, , [3, 6]], cost: new Map([['stone', 1], ['glass', 1]]), freeWith: ['Caravansery'], goldPer: new Map([['commerce', 1]]), pointsPer: new Map([['commerce', 1]]) },
+  { type: 'culture', name: 'Gardens', appears: [, , [3, 4]], cost: new Map([['brick', 2], ['wood', 1]]), points: 5 },
+  { type: 'culture', name: 'Palace', appears: [, , [3, 7]], cost: new Map([['wood', 1], ['brick', 1], ['stone', 1], ['ore', 1], ['glass', 1], ['cloth', 1], ['paper', 1]]), points: 8 },
+  { type: 'culture', name: 'Pantheon', appears: [, , [3, 6]], cost: new Map([['brick', 2], ['ore', 1], ['glass', 1], ['paper', 1], ['cloth', 1]]), freeWith: ['Temple'], points: 7 },
+  { type: 'culture', name: 'Senate', appears: [, , [3, 5]], cost: new Map([['wood', 2], ['ore', 1], ['stone', 1]]), freeWith: ['Library'], points: 6 },
+  { type: 'culture', name: 'Town Hall', appears: [, , [3, 5, 6]], cost: new Map([['stone', 2], ['ore', 1], ['glass', 1]]), points: 6 },
+  { type: 'military', name: 'Arsenal', appears: [, , [3, 4, 7]], cost: new Map([['wood', 2], ['ore', 1], ['cloth', 1]]), shields: 3 },
+  { type: 'military', name: 'Circus', appears: [, , [4, 5, 6]], cost: new Map([['stone', 3], ['ore', 1]]), freeWith: ['Training Ground'], shields: 3 },
+  { type: 'military', name: 'Fortifications', appears: [, , [3, 7]], cost: new Map([['ore', 3], ['stone', 1]]), freeWith: ['Walls'], shields: 3 },
+  { type: 'military', name: 'Siege Workshop', appears: [, , [3, 5]], cost: new Map([['brick', 3], ['wood', 1]]), freeWith: ['Laboratory'], shields: 3 },
+  { type: 'science', name: 'Academy', appears: [, , [3, 7]], cost: new Map([['stone', 3], ['glass', 1]]), freeWith: ['School'], sciences: new Set(['research']) },
+  { type: 'science', name: 'Lodge', appears: [, , [3, 6]], cost: new Map([['brick', 2], ['paper', 1], ['cloth', 1]]), freeWith: ['Dispensary'], sciences: new Set(['research']) },
+  { type: 'science', name: 'Observatory', appears: [, , [3, 7]], cost: new Map([['ore', 2], ['glass', 1], ['cloth', 1]]), freeWith: ['Laboratory'], sciences: new Set(['engineering']) },
+  { type: 'science', name: 'Study', appears: [, , [3, 5]], cost: new Map([['wood', 1], ['paper', 1], ['cloth', 1]]), freeWith: ['School'], sciences: new Set(['engineering']) },
+  { type: 'science', name: 'University', appears: [, , [3, 4]], cost: new Map([['wood', 2], ['paper', 1], ['glass', 1]]), freeWith: ['Library'], sciences: new Set(['education']) },
+]
+const structuresGuilds: Structure[] = [
+  { type: 'guild', name: 'Builders Guild', cost: new Map([['stone', 2], ['brick', 2], ['glass', 1]]), pointsPer: new Map([['wonder stage', 1]]), pointsPerNeighbor: new Map([['wonder stage', 1]]) },
+  { type: 'guild', name: 'Craftsmens Guild', cost: new Map([['ore', 2], ['stone', 2]]), pointsPerNeighbor: new Map([['advanced industry', 2]]) },
+  { type: 'guild', name: 'Magistrates Guild', cost: new Map([['wood', 3], ['stone', 1], ['cloth', 1]]), pointsPerNeighbor: new Map([['culture', 1]]) },
+  { type: 'guild', name: 'Philosophers Guild', cost: new Map([['brick', 3], ['paper', 1], ['cloth', 1]]), pointsPerNeighbor: new Map([['science', 1]]) },
+  { type: 'guild', name: 'Scientists Guild', cost: new Map([['ore', 2], ['wood', 2], ['paper', 1]]), sciences: new Set(['engineering', 'research', 'education']) },
+  { type: 'guild', name: 'Shipowners Guild', cost: new Map([['wood', 3], ['glass', 1], ['paper', 1]]), pointsPer: new Map([['basic industry', 1], ['advanced industry', 1], ['guild', 1]]) },
+  { type: 'guild', name: 'Spies Guild', cost: new Map([['brick', 3], ['glass', 1]]), pointsPerNeighbor: new Map([['military', 1]]) },
+  { type: 'guild', name: 'Strategists Guild', cost: new Map([['ore', 2], ['stone', 1], ['cloth', 1]]), pointsPerNeighbor: new Map([['defeat', 1]]) },
+  { type: 'guild', name: 'Traders Guild', cost: new Map([['glass', 1], ['paper', 1], ['cloth', 1]]), pointsPerNeighbor: new Map([['commerce', 1]]) },
+  { type: 'guild', name: 'Workers Guild', cost: new Map([['ore', 2], ['brick', 1], ['stone', 1], ['wood', 1]]), pointsPerNeighbor: new Map([['basic industry', 2]]) },
+]
+export const structures = new Map([structuresAge1, structuresAge2, structuresAge3, structuresGuilds].flat().map(c => ([c.name, c])))
+// Initialize 'freeWith' properties
+for (const structure of structures.values()) {
+  for (const precursorName of structure.freeWith ?? []) {
+    const precursor = structures.get(precursorName)!
+    if (precursor.paysFor === undefined) {
+      precursor.paysFor = [structure.name]
+    } else {
+      precursor.paysFor.push(structure.name)
+    }
+  }
+}
+
+export function buildDeck(age: number, numPlayers: number) {
+  if (age < minAge || age > maxAge || !isInteger(age)) {
+    throw new Error(`Unsupported age ${age}`)
+  }
+  if (numPlayers < minPlayers || numPlayers > maxPlayers || !isInteger(numPlayers)) {
+    throw new Error(`Unsupported player count ${numPlayers}`)
+  }
+  const cards: Structure[] = [...structures.values()].flatMap(structure =>
+    structure.appears?.[age - 1]
+      ?.filter(minPlayers => numPlayers <= minPlayers)
+      ?.map(() => structure)
+      ?? []
+  )
+  if (age === maxAge) {
+    cards.push(...sampleSize(structuresGuilds, numPlayers + 2))
+  }
+  return cards
+}
+
+export interface Wonder {
+  name: string
+  side: 'A' | 'B'
+  innateResource: Resource
+}
+
+export const wonders: Wonder[] = [
+  { name: 'Great Pyramid of Giza', side: 'A', innateResource: 'stone' },
+  { name: 'Great Pyramid of Giza', side: 'B', innateResource: 'stone' },
+  { name: 'Hanging Gardens of Babylon', side: 'A', innateResource: 'brick' },
+  { name: 'Hanging Gardens of Babylon', side: 'B', innateResource: 'brick' },
+  { name: 'Temple of Artemis at Ephesus', side: 'A', innateResource: 'paper' },
+  { name: 'Temple of Artemis at Ephesus', side: 'B', innateResource: 'paper' },
+  { name: 'State of Zeus at Olympia', side: 'A', innateResource: 'wood' },
+  { name: 'State of Zeus at Olympia', side: 'B', innateResource: 'wood' },
+  { name: 'Mausoleum at Halicarnassus', side: 'A', innateResource: 'cloth' },
+  { name: 'Mausoleum at Halicarnassus', side: 'B', innateResource: 'cloth' },
+  { name: 'Colossus of Rhodes', side: 'A', innateResource: 'ore' },
+  { name: 'Colossus of Rhodes', side: 'B', innateResource: 'ore' },
+  { name: 'Lighthouse of Alexandria', side: 'A', innateResource: 'glass' },
+  { name: 'Lighthouse of Alexandria', side: 'B', innateResource: 'glass' },
+]
+
+export interface TurnPlan {
+  action: 'structure' | 'discard'
+  cardIdx: number
+  goldLeft: number
+  goldRight: number
+}
+
+export interface Player {
+  name: string
+  wonder?: Wonder
+  gold: number
+  structures: {
+    age: number
+    structure: string
+  }[]
+
+  hand: string[]
+  turnPlan?: TurnPlan
+
+  leftBattles: number[]
+  rightBattles: number[]
+}
+
+export interface State {
+  stage: 'starting' | 'play' | 'finished'
+  players: Player[]
+
+  age?: number
+  turnsRemaining?: number
+  discard: string[]
+}
+
+export const initial: State = {
+  stage: 'starting',
+  players: [],
+  discard: [],
+}
+
+export interface BaseAction {
+  type: string
+}
+export interface AddPlayerAction extends BaseAction {
+  type: 'add player'
+  name: string
+}
+export interface StartGameAction extends BaseAction {
+  type: 'start game'
+}
+export interface PlanTurnAction extends BaseAction {
+  type: 'plan turn'
+  playerIdx: number
+  turnPlan?: TurnPlan
+}
+export interface ResetAction extends BaseAction {
+  type: 'reset'
+}
+export type Action = AddPlayerAction | StartGameAction
+  | PlanTurnAction
+  | ResetAction
+
+function sumCountable(player: Player, countable: Countable): number {
+  switch (countable) {
+    case 'wonder stage':
+      return 0 // TODO
+    case 'defeat':
+      return [...player.leftBattles, ...player.rightBattles].filter(b => b === defeatPoints).length
+    default:
+      return player.structures.filter(({ structure }) => structures.get(structure)?.type === countable).length
+  }
+}
+function sumCountableMap(player: Player, map: Map<Countable, number>): number {
+  return sum([...map.entries()].map(([countable, number]) => number * sumCountable(player, countable)))
+}
+function scoreScience(
+  sciences: Set<Science>[],
+  counts: Map<Science, number> = new Map([['engineering', 0], ['research', 0], ['education', 0]]),
+): number {
+  if (sciences.length === 0) {
+    return (scienceSetPoints * (min([...counts.values()]) ?? 0))
+      + sum([...counts.values()].map(c => c * c))
+  } else {
+    return max([...head(sciences)!.values()].map(science =>
+      scoreScience(tail(sciences), new Map([...counts, [science, (counts.get(science) ?? 0) + 1]]))
+    )) ?? 0
+  }
+}
+export function countPoints(state: State, playerIdx: number): number {
+  const player = state.players[playerIdx]
+  const left = state.players[(playerIdx + 1) % state.players.length]
+  const right = state.players[(playerIdx - 1 + state.players.length) % state.players.length]
+  return sum(player.leftBattles) + sum(player.rightBattles)
+    + sum(player.structures.map(({ structure }) => {
+      const card = structures.get(structure)!
+      return (card.points ?? 0)
+        + sumCountableMap(player, card.pointsPer ?? new Map())
+        + sumCountableMap(left, card.pointsPerNeighbor ?? new Map())
+        + sumCountableMap(right, card.pointsPerNeighbor ?? new Map())
+    }))
+    + Math.floor(player.gold / goldPerPoint)
+    + scoreScience(player.structures.flatMap(({ structure }) => {
+      const sciences = structures.get(structure)?.sciences
+      return sciences === undefined ? [] : [sciences]
+    }))
+}
+function beginAge(state: State): State {
+  const age = (state.age ?? minAge - 1) + 1
+  const deck = shuffle(buildDeck(age, state.players.length).map(s => s.name))
+  const handSize = Math.ceil(deck.length / state.players.length)
+  const hands = chunk(deck, handSize)
+  return {
+    ...state,
+    age,
+    turnsRemaining: handSize - 1,
+    players: state.players.map((p, i) => ({ ...p, hand: hands[i] })),
+  }
+}
+function countShields(player: Player): number {
+  return sum(player.structures.map(({ structure }) => structures.get(structure)?.shields))
+}
+function battleResult(state: State, playerIdx: number, delta: number): number | undefined {
+  const playerShields = countShields(state.players[playerIdx])
+  const otherShields = countShields(state.players[(playerIdx + delta + state.players.length) % state.players.length])
+  if (playerShields > otherShields) {
+    return victoryPoints[state.age!]
+  } else if (playerShields < otherShields) {
+    return defeatPoints
+  }
+}
+function endAge(state: State): State {
+  return {
+    ...state,
+    turnsRemaining: undefined,
+    discard: [...state.discard, ...state.players.flatMap(p => p.hand)],
+    players: state.players.map((p, i) => {
+      const left = battleResult(state, i, 1)
+      const right = battleResult(state, i, -1)
+      return {
+        ...p,
+        hand: [],
+        leftBattles: [...p.leftBattles, ...(left === undefined ? [] : [left])],
+        rightBattles: [...p.rightBattles, ...(right === undefined ? [] : [right])],
+      }
+    }),
+  }
+}
+function doTurn(state: State): State {
+  state = {
+    ...state,
+    players: state.players.map((player, playerIdx) => {
+      const turnPlan = player.turnPlan!
+      const left = state.players[(playerIdx + 1) % state.players.length]
+      const right = state.players[(playerIdx - 1 + state.players.length) % state.players.length]
+      const card = structures.get(player.hand[turnPlan.cardIdx])!
+
+      return {
+        ...player,
+        gold: player.gold
+          + left.turnPlan!.goldRight + right.turnPlan!.goldLeft
+          + (turnPlan.action === 'discard' ? 3 : 0)
+          + (turnPlan.action !== 'structure' ? 0 :
+            (card.gold ?? 0)
+            + sumCountableMap(player, card.goldPer ?? new Map())
+            + sumCountableMap(left, card.goldPerNeighbor ?? new Map())
+            + sumCountableMap(right, card.goldPerNeighbor ?? new Map())
+          ),
+        hand: [
+          ...player.hand.slice(0, turnPlan.cardIdx),
+          ...player.hand.slice(turnPlan.cardIdx + 1)
+        ],
+        structures: [
+          ...player.structures,
+          ...(turnPlan.action !== 'structure' ? [] : [
+            { age: state.age!, structure: player.hand[turnPlan.cardIdx] }
+          ]),
+        ]
+      }
+    }),
+    turnsRemaining: state.turnsRemaining! - 1,
+  }
+  if (state.turnsRemaining === 0) {
+    state = endAge(state)
+    if (state.age === maxAge) {
+      return {
+        ...state,
+        stage: 'finished',
+        age: undefined,
+      }
+    } else {
+      return beginAge(state)
+    }
+  } else {
+    const delta = state.age! % 2 === 1 ? -1 : 1
+    return {
+      ...state,
+      players: state.players.map((p, i) => ({
+        ...p,
+        hand: state.players[(i + delta + state.players.length) % state.players.length].hand,
+      })),
+    }
+  }
+}
+const reducers: { [type: string]: (state: State, action: any) => State } = {
+  'add player': (state, action: AddPlayerAction) => {
+    if (state.stage !== 'starting') { return state }
+    return {
+      ...state,
+      players: [...state.players, {
+        name: action.name,
+        gold: startingGold,
+        structures: [],
+        hand: [],
+        leftBattles: [],
+        rightBattles: [],
+      }],
+    }
+  },
+  'start game': state => {
+    if (state.stage !== 'starting' || state.players.length < minPlayers || state.players.length > maxPlayers) {
+      return state
+    }
+    return beginAge({ ...state, stage: 'play' })
+  },
+  'plan turn': (state, action: PlanTurnAction) => {
+    if (state.stage !== 'play') {
+      return state
+    }
+    const newState = {
+      ...state,
+      players: state.players.map(
+        (p, i) => i !== action.playerIdx ? p : { ...p, turnPlan: action.turnPlan }
+      ),
+    }
+    return newState.players.every(p => p.turnPlan !== undefined) ? doTurn(newState) : newState
+  },
+  reset: () => initial,
+}
+export function reducer(state: State, action: Action): State {
+  return reducers[action.type](state, action)
+}
diff --git a/packages/wonders-common/package.json b/packages/wonders-common/package.json
new file mode 100644
index 0000000..952c1e5
--- /dev/null
+++ b/packages/wonders-common/package.json
@@ -0,0 +1,27 @@
+{
+  "name": "wonders-common",
+  "version": "0.1.3",
+  "description": "WebSocket-based rollback state synchronization server.",
+  "main": "dist/index.js",
+  "license": "MIT",
+  "private": true,
+  "dependencies": {
+    "ketchup-common": "^0.1.1",
+    "lodash": "^4.17.20"
+  },
+  "devDependencies": {
+    "@tsconfig/node14": "^1.0.0",
+    "@types/jest": "^26.0.20",
+    "@types/lodash": "^4.14.168",
+    "@types/node": "^14.14.22",
+    "@typescript-eslint/eslint-plugin": "^4.14.1",
+    "@typescript-eslint/parser": "^4.14.1",
+    "eslint": "^7.18.0",
+    "jest": "^26.6.3",
+    "ts-jest": "^26.5.0",
+    "typescript": "^4.1.3"
+  },
+  "scripts": {
+    "build": "tsc"
+  }
+}
diff --git a/packages/wonders-common/tsconfig.json b/packages/wonders-common/tsconfig.json
new file mode 100644
index 0000000..41c42e8
--- /dev/null
+++ b/packages/wonders-common/tsconfig.json
@@ -0,0 +1,7 @@
+{
+  "extends": "@tsconfig/node14/tsconfig.json",
+  "compilerOptions": {
+    "rootDir": ".",
+    "outDir": "dist"
+  }
+}
diff --git a/packages/wonders-server/.eslintrc.json b/packages/wonders-server/.eslintrc.json
new file mode 100644
index 0000000..c22f690
--- /dev/null
+++ b/packages/wonders-server/.eslintrc.json
@@ -0,0 +1,23 @@
+{
+    "env": {
+        "es2021": true,
+        "node": true
+    },
+    "extends": [
+        "standard"
+    ],
+    "parser": "@typescript-eslint/parser",
+    "parserOptions": {
+        "ecmaVersion": 12,
+        "sourceType": "module"
+    },
+    "plugins": [
+        "@typescript-eslint"
+    ],
+    "rules": {
+      "comma-dangle": ["error", "only-multiline"],
+      "padded-blocks": "warn",
+      "no-multiple-empty-lines": "warn",
+      "space-before-function-paren": "off"
+    }
+}
diff --git a/packages/wonders-server/Dockerfile b/packages/wonders-server/Dockerfile
new file mode 100644
index 0000000..6586501
--- /dev/null
+++ b/packages/wonders-server/Dockerfile
@@ -0,0 +1,20 @@
+FROM node:16-alpine
+
+RUN apk add --no-cache tini
+
+RUN yarn global add lerna
+
+WORKDIR /opt/example-server
+COPY packages/ketchup-common/package.json packages/ketchup-common/
+COPY packages/ketchup-server/package.json packages/ketchup-server/
+COPY packages/example-common/package.json packages/example-common/
+COPY packages/example-server/package.json packages/example-server/
+COPY package.json yarn.lock lerna.json ./
+RUN lerna bootstrap
+
+COPY . ./
+RUN lerna run build
+
+ENTRYPOINT ["tini", "--"]
+CMD ["node", "packages/example-server"]
+EXPOSE 80
diff --git a/packages/wonders-server/index.ts b/packages/wonders-server/index.ts
new file mode 100644
index 0000000..6985f4d
--- /dev/null
+++ b/packages/wonders-server/index.ts
@@ -0,0 +1,22 @@
+import WebSocket from 'ws'
+import KetchupServer from 'ketchup-server'
+import { initial, reducer } from 'wonders-common'
+
+const port = parseInt(process.env.PORT ?? '80')
+
+const wss = new WebSocket.Server({ port })
+
+const ks = new KetchupServer(initial, reducer)
+
+wss.on('connection', ws => {
+  ks.addRemoteClient(ws)
+})
+
+console.log(`Listening on ${port}`)
+
+function shutdown() {
+  console.log('Shutting down')
+  wss.close()
+}
+process.on('SIGINT', shutdown)
+process.on('SIGTERM', shutdown)
diff --git a/packages/wonders-server/package.json b/packages/wonders-server/package.json
new file mode 100644
index 0000000..c4821bf
--- /dev/null
+++ b/packages/wonders-server/package.json
@@ -0,0 +1,36 @@
+{
+  "name": "wonders-server",
+  "version": "0.1.3",
+  "description": "WebSocket-based rollback state synchronization server.",
+  "main": "dist/index.js",
+  "license": "MIT",
+  "private": true,
+  "dependencies": {
+    "ketchup-server": "^0.1.1",
+    "lodash": "^4.17.20",
+    "wonders-common": "^0.1.1",
+    "ts-node": "^9.1.1",
+    "ws": "^7.4.2"
+  },
+  "devDependencies": {
+    "@tsconfig/node14": "^1.0.0",
+    "@types/jest": "^26.0.20",
+    "@types/lodash": "^4.14.168",
+    "@types/node": "^14.14.22",
+    "@types/ws": "^7.4.0",
+    "@typescript-eslint/eslint-plugin": "^4.14.1",
+    "@typescript-eslint/parser": "^4.14.1",
+    "eslint": "^7.18.0",
+    "jest": "^26.6.3",
+    "ts-jest": "^26.5.0",
+    "typescript": "^4.1.3"
+  },
+  "optionalDependencies": {
+    "bufferutil": "^4.0.3",
+    "utf-8-validate": "^5.0.4"
+  },
+  "scripts": {
+    "build": "tsc",
+    "start": "node dist"
+  }
+}
diff --git a/packages/wonders-server/tsconfig.json b/packages/wonders-server/tsconfig.json
new file mode 100644
index 0000000..41c42e8
--- /dev/null
+++ b/packages/wonders-server/tsconfig.json
@@ -0,0 +1,7 @@
+{
+  "extends": "@tsconfig/node14/tsconfig.json",
+  "compilerOptions": {
+    "rootDir": ".",
+    "outDir": "dist"
+  }
+}