AI-friendly board game rules summaries — use with Claude, ChatGPT, or any AI assistant
Players settle the island of Catan by building roads, settlements, and cities. Resources are produced by dice rolls and collected by players with buildings adjacent to the producing terrain hexes. Players trade resources with each other and the bank to fund construction. The first player to reach 10 victory points on their turn wins.
Beginner setup: Place terrain hexes, number tokens, and starting settlements/roads in the fixed positions shown in the rulebook illustration.
Variable setup (recommended for experienced players):
Each player takes: 5 settlements, 4 cities, 15 roads, 1 building costs card.
Set-up phase (2 rounds):
Round 1: Roll dice; highest roller goes first. Starting player places 1 settlement on any unoccupied intersection + 1 adjacent road. Continue clockwise — each player places 1 settlement + 1 road. Distance Rule applies.
Round 2: The last player from Round 1 goes first. Each player places a second settlement + adjacent road, going counterclockwise (so the starting player from Round 1 places last). After placing the second settlement, immediately take 1 resource card for each terrain hex adjacent to that second settlement.
Place the robber on the desert. Place “Longest Road” and “Largest Army” special cards beside the board. Sort resource cards into 5 face-up stacks. Shuffle development cards face-down.
The starting player (who placed last in Round 2) takes the first turn.
On your turn, perform these phases in order:
You may play 1 development card at any time during your turn (before or after rolling). Pass dice left when done.
Advanced variant (Combined Trade/Build Phase): After rolling, trade and build in any order, interleaving freely. You can use a harbor on the same turn you build a settlement there.
Roll both dice and sum them. Every player who has a settlement or city adjacent to a terrain hex with that number receives resources:
Supply shortage: If the bank doesn’t have enough of a resource to pay all players, no one receives that resource this turn. Exception: If the shortage only affects 1 player, that player receives as many as remain in the supply.
The robber blocks production on the hex it occupies — buildings adjacent to the robber’s hex produce nothing when that number is rolled.
When a 7 is rolled, no one receives resources. Instead:
The robber remains on its new hex, blocking resource production there until moved again.
On your turn, after rolling, you may trade resource cards with other players. You announce offers, others can counter-offer. Any ratio is allowed (e.g., 1-for-1, 2-for-1, etc.).
Rules:
On your turn, trade with the bank (no other player needed):
| Harbor type | Rate | Condition |
|---|---|---|
| No harbor | 4:1 | Always available — trade 4 identical resource cards for any 1 |
| Generic harbor (3:1) | 3:1 | Must have settlement/city on the harbor — trade 3 identical for any 1 |
| Special harbor (2:1) | 2:1 | Must have settlement/city on the harbor — trade 2 of the specific resource shown for any 1 |
A special harbor’s 2:1 rate only applies to its depicted resource. You cannot trade other resources at 3:1 through a special harbor. You may not trade with the bank during another player’s turn.
Pay resource cards to the supply to build. You may build multiple things per turn if you have the resources. You are limited to the physical supply of pieces (5 settlements, 4 cities, 15 roads).
| Structure | Cost | Rules |
|---|---|---|
| Road | 1 Brick + 1 Lumber | Must connect to your existing road, settlement, or city. 1 road per path. |
| Settlement | 1 Brick + 1 Lumber + 1 Wool + 1 Grain | Must connect to your road. Must obey Distance Rule. |
| City (upgrade) | 3 Ore + 2 Grain | Replaces an existing settlement (return settlement to supply). Cannot build a city directly. |
| Development card | 1 Ore + 1 Wool + 1 Grain | Draw top card from deck. Keep hidden. Cannot buy if deck is empty. |
Distance Rule: A settlement may only be built on an intersection where all 3 adjacent intersections are vacant (no settlement or city, including your own).
Road placement: Roads are placed on paths (edges between hexes). Only 1 road per path. You can build roads along the coast. An opponent’s settlement/city on an intersection blocks your road from continuing through that intersection.
You may play 1 development card per turn (1 knight OR 1 progress card). You may play it at any time during your turn, even before rolling. You may not play a card bought the same turn.
Knight cards (purple, 14 in deck): Immediately move the robber (same rules as rolling a 7: move robber, then steal 1 card from an adjacent player). Played knights stay face-up in front of you.
Progress cards (green, 6 in deck):
Progress cards are removed from the game after use.
Victory Point cards (orange, 5 in deck): Keep hidden. Only reveal when you reach 10+ victory points on your turn to win. Exception: You may play/reveal VP cards on the turn you buy them if they give you 10 points. You may play multiple VP cards on the same turn.
Development cards cannot be traded or given away.
First player to reach 10 or more victory points on their turn wins immediately.
| Source | Victory Points |
|---|---|
| Settlement | 1 VP each |
| City | 2 VP each |
| Longest Road special card | 2 VP |
| Largest Army special card | 2 VP |
| Victory Point development card | 1 VP each |
Each player starts with 2 settlements = 2 VP. You need 8 more VP to win.
You can only win on your own turn. If you reach 10 VP during another player’s turn, you must wait until your turn to claim victory.
The likelihood of each dice total:
| Structure | Cost | |—|—| | Road | 1 Brick + 1 Lumber | | Settlement | 1 Brick + 1 Lumber + 1 Wool + 1 Grain | | City (upgrade) | 3 Ore + 2 Grain | | Development Card | 1 Ore + 1 Wool + 1 Grain |
| Terrain | Resource | |—|—| | Hills | Brick | | Forest | Lumber | | Mountains | Ore | | Fields | Grain | | Pasture | Wool | | Desert | Nothing |