snatchgame/gameRules.md

Snatch or Share - Game Logic

Game Overview

Snatch or Share is a multiplayer game that simulates governance evolution in decentralized exchanges, based on Elinor Ostrom's "Snatch Game".

Game State Structure

Main Game State

GameState {
  round: number (1-5)
  groups: Group[] // Groups of 3 players
  currentPhase: 'waiting' | 'trading' | 'judging' | 'results'
}

Group {
  id: string
  players: Player[3]
  currentJudge?: Player // Only in Round 5
  activeTradeOffers: TradeOffer[] // Multiple simultaneous offers
}

Player {
  id: string
  name: string
  producerRole: 'turkey' | 'coffee' | 'corn'
  tokens: {
    turkey: number
    coffee: number
    corn: number
  }
  points: number // Calculated: own_tokens * 1 + other_tokens * 2
  shameTokens: number // For Round 4
  isSuspended: boolean // For Round 5
  role: 'trader' | 'judge' // Only relevant in Round 5
}

TradeOffer {
  id: string
  offererId: string
  targetId: string
  offering: { turkey: number, coffee: number, corn: number }
  requesting: { turkey: number, coffee: number, corn: number }
  status: 'pending' | 'accepted' | 'rejected' | 'snatched' | 'cancelled'
}

Game Initialization

Room Configuration

• Exactly 3 players required to start the game
• Maximum 3 players per room

Producer Role Assignment

• Each player is randomly assigned one unique producer role:
  • Turkey Producer: Starts with 5 turkey tokens
  • Coffee Producer: Starts with 5 coffee tokens
  • Corn Producer: Starts with 5 corn tokens
• Roles cannot be repeated - exactly one producer of each type per game

Judge Role (Round 5)

• In Round 5, one player becomes Judge (rotates each round)
• Judge role is decorative - player keeps their original producer role
• Judge has additional responsibilities but maintains their trading capabilities

Round Flow (Focus: Round 1)

Round 1: State of Nature

• No time limits on turns
• Simultaneous trading: All players can make offers at the same time
• Offer limit: Each player can make maximum 2 offers to each opponent
• Offer format: "I give X tokens in exchange for Y tokens"
• Offer responses: Target player can Accept, Reject, or Snatch

Trading Mechanics

Making Offers

• Players can offer and request any amount of tokens (even more than they have)
• Offers are made simultaneously to multiple players
• Format: offering: {turkey: X, coffee: Y, corn: Z} for requesting: {turkey: A, coffee: B, corn: C}
• All trade offers are public - visible to all players in the room, not just offerer and target

Resolving Offers

• Accept: Trade executed to the extent possible with available tokens
• Reject: Offer cancelled, no exchange
• Snatch: Receiver gets offered tokens (up to what offerer has) without giving anything in return
• Cancel: Offerer can cancel pending offers

Partial Fulfillment

• All trades execute with available tokens only
• Example: Offer "6 corn for 6 coffee" but only have 5 corn → Execute "5 corn for 5 coffee"
• Example: Accept offer for 8 tokens but only have 3 → Give 3 tokens, receive offered amount
• No negative consequences for partial fulfillment - it's part of the game

Rules by Round

Round 1-2: State of Nature / Anarchy

• No special rules
• All players are Traders
• No enforcement mechanisms

Round 3: Counterproductive Rule

• Mandatory Rule: "All trade offers must be accepted"
• Players still have freedom to snatch
• Reduces agency, invites exploitation

Round 4: Soft Norms (Shame Tokens)

• Each player can assign 1 shame token per round
• If player starts round with 2+ shame tokens:
  • Loses 2 tokens before round begins
  • Barred from offering trades (can only respond)

Round 5: Governance Rules (Ostrom Adapted)

• Group Roles: Two Traders and One Judge
• Judge Role: Rotates each round
• Applied Rules:
  • Position Rule: Judge oversees fairness and conflict resolution
  • Boundary Rule: Only group members can trade; Judge may suspend rule-breaker for 1 round
  • Choice Rule: Trades are voluntary; Players can report snatching to Judge
  • Enforcement Rule: If Judge confirms snatch → goods returned + snatcher forfeits 3 tokens to victim
  • Aggregation Rule: Trade only completes with explicit mutual consent

Key Mechanics

Trading

• Exchange Amount: Always 5 tokens of player's own type
• Value System: own_tokens × 1 + other_tokens × 2
• Snatch: Take opponent's tokens without giving anything in return

Point Calculation Examples

• Holding 10 of own = 10 points
• Holding 5 of own + 5 of other = 15 points
• Holding 10 of own + 5 snatched = 20 points

Governance Evolution

• Round 1-2: No trust → no cooperation → suboptimal outcomes
• Round 4: Social deterrents emerge
• Round 5: Governance stabilizes expectations → trust emerges → optimal outcomes through fair trades