Vault Heist
Math sheet
Model vh-1-server · Updated 28 October 2026 · Virtual demo credits only.
A base stake B buys 12 reveals on a 6×6 board. Each symbol is an independent weighted draw with replacement, committed by the server before display. Position has no effect. After reveal 12, the player may finish or buy exactly one Extra Reveals pack: 0.25B for four more reveals. Maximum 16 reveals per round.
Return and win frequency
| Strategy | Theoretical RTP | Any payout |
|---|---|---|
| Never buy extras | 81.317551% | 95.600858% |
| Always buy extras | 90.400617% | 99.715662% |
| RTP-optimal optional extras | ≈95.95% | ≈99.71% |
Any payout is not necessarily a net profit. Optional strategy figures assume the full base round is played and sufficient balance is available for the purchase.
Symbol probabilities and awards
Each symbol pays once when its goal is reached. Different symbol awards stack; surplus copies of an already completed symbol do not pay again. Total weight: 10022.
| Symbol | Collect | Award / B | Weight | Per-reveal chance |
|---|---|---|---|---|
| 🍒 Cherries | 3 | 0.2× | 1940 | 19.3574% |
| 🍎 Apple | 3 | 0.5× | 2449 | 24.4362% |
| 🍌 Banana | 3 | 0.8× | 2260 | 22.5504% |
| 🍇 Grapes | 3 | 1× | 375 | 3.7418% |
| 🍓 Strawberry | 5 | 0.4× | 614 | 6.1265% |
| 🌼 Flower | 5 | 1× | 518 | 5.1686% |
| 🧱 Brick | 5 | 1.6× | 436 | 4.3504% |
| 🧀 Cheese | 5 | 2× | 355 | 3.5422% |
| 🍊 Orange | 8 | 0.8× | 237 | 2.3648% |
| 🍉 Melon | 8 | 1.5× | 185 | 1.8459% |
| 🍀 Clover | 8 | 2.5× | 145 | 1.4468% |
| 💎 Diamond | 8 | 3× | 105 | 1.0477% |
| 👑 Crown | 10 | 1.2× | 144 | 1.4368% |
| 💍 Gold ring | 10 | 2.3× | 115 | 1.1475% |
| 🪙 Gold coin | 10 | 3.8× | 86 | 0.8581% |
| 🧰 Treasure chest | 10 | 4.5× | 58 | 0.5787% |
Calculation
For symbol i, pᵢ = weightᵢ / 10022. For a fixed n reveals, expected return divided by B is Σᵢ mᵢ × P(Binomial(n, pᵢ) ≥ goalᵢ). Base RTP uses n=12. Always-buy RTP uses n=16 and divides expected return by 1.25.
Optional-purchase RTP is expected total payout divided by expected total stake, including extras. The RTP-optimal decision buys when the conditional expected extra payout / B exceeds approximately 0.239875. Maximizing expected net money instead uses 0.25. The displayed extra expectation is informational, not a guarantee.
Accounting and backend
Amounts use integer units of 0.0001 demo dollar. Bets accept up to two decimal places; a $0.01 bet has a $0.0025 extra-pack price. Awards are credited as they occur. Net result = total awards − base stake − extra cost. No rounding to cents is performed between actions.
Supabase stores the session, round, revealed symbols, request history and ledger. Server cryptographic rejection sampling selects weighted outcomes. Requests are serialized and idempotent; retries do not duplicate bets or prizes. Reload resumes the server round. Only the already-paid sequence is disclosed: 12 results after the base debit, and four further results only after the extra fee. Clicks show those committed symbols immediately and synchronize ordered reveal batches in the background. Displayed awards reconcile with the server ledger; the browser cannot select outcomes or settle money. New financial actions synchronize first.
No claim of an independently certified RNG or a public provably-fair commitment protocol is made. The 8- and 10-symbol awards are extremely rare with at most 16 independent draws.
Reproduce
node tools/verify-vault-heist-math.mjsnode tools/test-vault-heist-backend.mjs <staging-endpoint>