name: coin flip
aliases: [coinflip, coin_flip, coin-flip, coin]
category: Interaction
related: [casino, cash hunt, pachinko]
description: |
  COIN FLIP — a fair 50/50 coin with two spinning faces.

  play coin flip             Take the single seat.
  bet 10                     Stake 10 (the house reserves 1000); the faces spin.
  bet / rebet                Repeat your last stake.
  stop                       Leave after the coin has landed.

  Each round the RED face spins like a wheel and lands a negative multiplier
  from 0 to -100. The BLUE face then spins and lands a positive multiplier
  from 0 to +100, with a middle band (63-77 and 90) removed so the two faces
  still average a -2 swing. The landed multipliers print, then the fair
  50/50 coin flips. A settled coin is filled in solid red or blue.

  The multiplier is a NET swing on your stake, so red -50 loses half your
  stake, blue +50 wins half your stake, red -100 loses it all, and blue +100
  doubles it. Multipliers include the stake; +0x is a push.

  Because the swing can reach 100x your stake, the house requires you to
  hold 100x your stake and reserves exactly that when you bet. Your payout
  is (100 + swing) x stake, so it is never negative: a -100 red simply
  returns zero. The reserve and the payout are one settled transaction.

  The coin is exactly fair. The 2% house edge comes from the two faces:
  red is uniform over 0..100 and blue drops a middle band to a mean of +46,
  so the two distributions average a -2 swing per stake — exactly 98% RTP.

  You cannot leave mid-round. Shutdown refunds an unsettled round; a failed
  payout keeps your stake pending for recovery and settle retries the same
  landed face.