From ced77d7c89129da6ba4001ab8e3dad265aa41396 Mon Sep 17 00:00:00 2001
From: historia <[not public]>
Date: Fri, 9 Oct 2026 17:05:54 -0400
Subject: feat: new casino game: coin flip

---
 building_guide/rooms.md | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

(limited to 'building_guide')

diff --git a/building_guide/rooms.md b/building_guide/rooms.md
index 608dcf5..c61e710 100644
--- a/building_guide/rooms.md
+++ b/building_guide/rooms.md
@@ -246,7 +246,7 @@ Multiplayer table fields (`casino_tables`):
 | Field | Type | Default | Notes |
 |---|---|---|---|
 | `id` | string | — | Required. Nonempty, no surrounding whitespace, unique among the room's tables and machines. |
-| `game` | string | — | Required. `blackjack`, `baccarat`, `roulette`, `craps`, `paigow`, `video_poker`, `plinko`, `pachinko`, or `cash_hunt`. |
+| `game` | string | — | Required. `blackjack`, `baccarat`, `roulette`, `craps`, `paigow`, `video_poker`, `plinko`, `pachinko`, `cash_hunt`, or `coin_flip`. |
 | `max_players` | int | 8 | 0–64. Video poker is forced to 1; Pai Gow caps at 6. |
 | `betting_ticks` | int | 20 | 0–3600. |
 | `min_bet` | int | 1 | Must not exceed `max_bet`. |
@@ -311,6 +311,27 @@ round and the best-slot return is exactly 100%. `max_players` must be omitted,
 space can chain an arbitrarily large payout; any return beyond the economy's
 credit cap is clamped rather than rejected.
 
+#### Coin Flip
+
+Coin Flip is a single-seat fixture under `casino_tables`, addressed with
+`play coin flip`:
+
+```yaml
+casino_tables:
+  - id: coin_flip
+    game: coin_flip
+    min_bet: 1
+    max_bet: 10000
+```
+
+No game-specific rule block is needed. The coin is a fair 50/50: red lands a
+negative net multiplier (0 to -100), blue a positive one (0 to +100 with a
+removed middle band so its mean stays +46), and the two faces average a -2
+swing for exactly 98% RTP. Because the swing can reach 100x the stake, a bet
+of `N` reserves `100 * N` from the wallet, so the player must hold 100x their
+stake. `max_players` must be omitted, `0`, or `1`, and `max_bet` cannot exceed
+`MaxCredits / 100`.
+
 #### Blackjack
 
 ```yaml
-- 
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