01
Game background
Fire Keno is a 20-of-80 draw game supporting 2–10 selections and a selection-specific paytable. It is a compact case for secure sampling, strict input validation, and exact hit-to-multiplier lookup.
native.typescript / Slotopol
Fire Keno
An interactive number board backed by secure server-side drawing and paytable evaluation.
connecting
Demo credits1,000.00
Selected0 / 10
Last payout0.00
Source RTP92.0289%
Select 2–10 numbersREADY
Select at least 2 numbers.
engineering.case-study
Inside the Fire Keno system boundary.
What the player experiences, what the implementation actually owns, and where production responsibilities would begin.
02
How the game works
- Select 2–10 distinct values from 1–80.
- Choose a virtual stake and submit the draw.
- The backend draws 20 unique values and counts selected hits.
- The matching Fire Keno paytable cell produces the payout multiplier.
03
Backend architecture
The reusable KenoApiService owns an expiring session and delegates the draw to FireKenoGame. A shared cryptographic sampler generates unique values; the game owns board-state encoding and paytable lookup.
ClientREST APISelection validationCrypto drawHit scannerPayout
04
System boundaries
- Game Client
- Presentation, input, accessibility, and demo-credit display.
- REST API
- Request validation and routing into one isolated game session.
- Game Session
- Ephemeral configuration and the previous authoritative result.
- Game Engine / RNG
- Outcome generation, game rules, win evaluation, and result contracts.
- Hit Scanner / Paytable
- Intersection count and Fire Keno multiplier selection.
05
Critical engineering decisions
- Reject duplicates and out-of-range selections.
- Sample without replacement using a reusable crypto primitive.
- Encode selected, drawn, and hit cells in server state.
- Keep the imported paytable exact and cover it with a deterministic test.
06
Failure handling
- A client disconnect does not rewrite a completed server result; reconnecting requires the session identifier while it remains in memory.
- An unknown or expired session is rejected instead of silently creating a replacement outcome.
- A timed-out spin or draw should not be blindly retried as though commands were idempotent; these demos do not yet persist command identifiers.
- The browser’s virtual credits are not a ledger. If UI credit state is lost, it cannot be reconstructed from these focused game-engine modules.
07
Fairness / RNG
A cryptographic Fisher–Yates sampler draws 20 unique numbers on the backend. The source RTP is disclosed as model metadata; there is no certification or provably-fair commitment.
08
Conceptual data model
- gameId- betAmount- selectedNumbers- lastActivity- drawnNumbers- selectedNumbers- screen- selected- hits- multiplier- payout