# hizi engine SDK: frontend guide

> Build a game frontend with the engine SDK. Choose the pages needed for your task.

Read Build a Frontend in order. Then read your game guide and the relevant SDK references.
Check Source Audit and Gaps before implementation. Use the Release Checklist before release.

## Reading options

- [Complete frontend text](https://docs.hizi.io/engine/sdk/llms-full.txt): All SDK and game guides, Operator Interface docs, and example source.
- [Operator Interface index](https://docs.hizi.io/operator-interface/llms.txt): Setup, events, methods, and operator-specific guides.
- [Engine index](https://docs.hizi.io/engine/llms.txt): Engine configuration, generation, and other engine topics.
- [Site index](https://docs.hizi.io/llms.txt): Other platform documentation.

## Build a Frontend

- [Build a frontend with the hizi engine SDK](https://docs.hizi.io/engine/sdk/): The complete frontend implementation path: loading, stakes, rules, operator integration, recovery, jurisdiction controls, and all 14 creator modes.
- [Getting started](https://docs.hizi.io/engine/sdk/getting-started.html): Install the audited SDK version. Call login() once, load configuration, and restore the round before enabling play.
- [Launch and loading screens](https://docs.hizi.io/engine/sdk/launch-and-loading.html): Launch metadata, loading screens, required messages, asset loading, audio ownership, and the ready handshake.
- [Stakes and money](https://docs.hizi.io/engine/sdk/stakes-and-money.html): Minor units, stake overrides, custom ladders, purchase limits, resumed base stakes, and session net position.
- [Game flow](https://docs.hizi.io/engine/sdk/game-flow.html): A checked slot controller with request locking, timing, explicit choices, banking, freeplays, and recovery after uncertain responses.
- [Rules and slot presentation](https://docs.hizi.io/engine/sdk/rules-and-presentation.html): The slot configuration for rules and paytables, supported mechanics, missing presentation data, and approved math inputs.
- [Operator Interface](https://docs.hizi.io/engine/sdk/operator-interface.html): Links to the existing Operator Interface setup, events, methods, and operator-specific guides.
- [Jurisdictions and responsible gambling](https://docs.hizi.io/engine/sdk/jurisdictions.html): All 13 Hizi jurisdiction presets, UKGC product requirements, player limits, reality checks, and release decisions.
- [Recovery and session management](https://docs.hizi.io/engine/sdk/recovery-and-session.html): Restore active rounds, reconcile lost responses, refresh credentials, preserve session totals, and process exits safely.
- [Frontend release checks](https://docs.hizi.io/engine/sdk/release-checklist.html): Acceptance fixtures for slots, every vertical, operator protocols, reconnects, and jurisdiction controls.

## SDK Reference

- [Frontend settings reference](https://docs.hizi.io/engine/sdk/settings-reference.html): Every SDK game setting, Hizi extensions, units, defaults, and required frontend behavior.
- [Response Handling](https://docs.hizi.io/engine/sdk/response-handling.html): The `IGameResult` shape - `scenario`, `engineData` (`entryIndex`, `scenarioInfo`, `spinInfo`, `playerChoice` (union of feature-spin and cash options; use `isFeatureChoice`/`isCashChoice` guards), `progressionCounters`, `progressionEvents`, `canCollect`, `currentFeature`, `nextFeature`), and win/balance fields.
- [Error handling](https://docs.hizi.io/engine/sdk/error-handling.html): The `TNetworkResponse<T>` discriminated union, `IErrorResponse.code` (`string`, compare against `API_RETURNCODES` values), `recoverableErrorCodes`, and the always-check-`success`-first pattern.
- [Buy-Features](https://docs.hizi.io/engine/sdk/buy-features.html): Use the published feature price and RTP. Validate the full debit and restore the original base stake.
- [Gamble and collection](https://docs.hizi.io/engine/sdk/gamble-features.html): Current card IDs, ladder state, collect-or-continue decisions, and partial banking without an immediate wallet credit.
- [Freeplays](https://docs.hizi.io/engine/sdk/free-plays.html): Freeplays granted by an operator - fixed stake, optional fixed feature, read from `freePlaysAvailable` and spent with `placeBet`. Granting and revoking happen out-of-band through the Operator API; there is no claim endpoint.
- [RGS features and promotions](https://docs.hizi.io/engine/sdk/rgs-features.html): Frontend responsibilities for freeplays, discounts, packages, shared jackpots, history, provably fair results, and operator extensions.
- [Progression Counters](https://docs.hizi.io/engine/sdk/progression-counters.html): Per-player counters that accumulate toward 1.0 - `randomChoice`/`playerChoice` selection, mixed feature-spin and cash-multiplier awards, stake-specific persistence.
- [Crash transport](https://docs.hizi.io/engine/sdk/crash-transport.html): A checked WebSocket transport for Crash requests and broadcasts on one connection. No automatic money-request retries.
- [Endpoints](https://docs.hizi.io/engine/sdk/endpoints.html): The exact HTTP operations, SDK options, reply shapes, scenario decoding, and session methods.
- [Types & Interfaces](https://docs.hizi.io/engine/sdk/types.html): Engine result types re-exported from the SDK - `IGameResult`, `IScenarioInfo`, `ISpinInfo`, `IBuyFeatureOption`, `ILoadConfigConfig`, `IProgressionCounterConfig`, `IProgressionEvent`, `TPlayerChoiceAward`, `TPlayerChoiceFeatureAward`, `TPlayerChoiceCashAward`.
- [Demo](https://docs.hizi.io/engine/sdk/demo.html): Link to the live "Fruits 95" reference game on the hizi staging environment.

## Game Guides

- [Game guides](https://docs.hizi.io/engine/games/): Index of per-game integration guides - each one explains the `scenario` shape returned by `placeBet`, any `additionalData` the round needs, and the collect-or-continue flow.
- [Slot Game Responses](https://docs.hizi.io/engine/games/slot.html): `IResult` from `@hizi.io/engine-sdk` - boards, wins, cascades, hold & win, sticky symbols, multiplier collection, wheel features.
- [Plinko Responses](https://docs.hizi.io/engine/games/plinko.html): Bucket-index scenario, row/risk selection via buy-features, multiplier lookup from `loadConfig`, ball-drop animation.
- [Frogger Game Responses](https://docs.hizi.io/engine/games/frogger.html): Multi-step wager-stake flow, risk selection via buy-features, cashout multiplier ladder from `loadConfig`, collect-or-continue loop.
- [Hi/Lo Game Responses](https://docs.hizi.io/engine/games/hilo.html): `playerChoice`-driven higher/lower/skip flow, dynamic card odds, skip re-deal within the round, multiplier rounding, collect-or-continue loop.
- [Mines Game Responses](https://docs.hizi.io/engine/games/mines.html): Pick positions sent via `additionalData`, the `board` tile-state array, mine-count selection via buy-features, cashout multiplier progression, collect-or-continue loop.
- [Keno Game Responses](https://docs.hizi.io/engine/games/keno.html): Player numbers via `additionalData` (or auto-pick), enriched `playerNumbers`/`drawnNumbers`, pick-count and risk selection via buy-features, pay-table rendering.
- [Bingo Game Responses](https://docs.hizi.io/engine/games/bingo.html): Single-call instant-win draw game - 1-6 tickets at a per-ticket stake, the drawn ball pool, daubed numbers and completed patterns. Covers the Bingo 75 / 90 / 80 templates and config-described boards. No continuation, no `playerChoice`, no `collect`.
- [Match game responses](https://docs.hizi.io/engine/games/match.html): EXACT and AT_LEAST matches, configuration tables, one-based matched slots, arrangement rendering, and immediate settlement.
- [Progressive game responses](https://docs.hizi.io/engine/games/progressive.html): A step ladder with absolute multipliers, survival results, explicit continuation, and cashout. This is not a shared jackpot.
- [Over/Under Game Responses](https://docs.hizi.io/engine/games/overunder.html): Single-roll instant resolution, threshold/direction selection via buy-features, multiplier lookup, win calculation.
- [Roulette Game Responses](https://docs.hizi.io/engine/games/roulette.html): Multi-bet rounds composed via `additionalData`, polymorphic `selection` per bet type, per-bet `settlement[]` (`won`/`payout`/`winAmount`), enriched scenario fields (`color`, `oddEven`, `dozen`, `column`), and the two RTP mechanisms.
- [Blackjack Game Responses](https://docs.hizi.io/engine/games/blackjack.html): Initial deal with optional side bets, multi-step action flow (`playerChoice`: hit/stand/double/split/insurance/evenMoney), final `IBlackjackScenario` with dealer, hands, side-bet results, and insurance payouts.
- [Crash game responses](https://docs.hizi.io/engine/games/crash.html): Open a round via `crashPlaceBetData`, listen to the server-driven curve over websocket events (`roundStarted`/`roundTick`/`betCashedOut`/`roundEnded`/`balanceUpdated`), trigger manual cashouts via `collect` + `crashCollectData`.
- [Blank and imported game outcomes](https://docs.hizi.io/engine/games/custom.html): The Blank creator mode preserves the imported game type. Define custom requests, scenarios, rules, and settlement explicitly.