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F007 — RTP Margin Application

FieldValue
IDF007
Phase1 — Core Game Engine
JiraHEDGE-133
StatusTS ⬜ · JS ⬜ · UMA ⬜

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Business Rule

The operator configures a target RTP at installation time. The game engine converts this into a house margin that is subtracted from the fair European odds before presenting them to the player. Relationship: 
houseMargin = 1 - targetRTP
payoutOdds  = fairOdds × (1 - houseMargin)
            = fairOdds × targetRTP
Example (97% RTP, 3% margin): 
fairOdds   = 1 / 0.25 = 4.00   (25% win probability)
margin     = 1 - 0.97 = 0.03
payoutOdds = 4.00 × 0.97 = 3.88
RTP proof: Over many plays, the expected value of the payout relative to the stake equals the target RTP: 
RTP = payoutOdds × winProbability
    = 3.88 × 0.25
    = 0.97 = 97%
The RTP figure is the target — actual achieved RTP is influenced by:
  1. The Rounding Algorithm applied to oddsActual (see F033)
  2. Player betting strategy (skilled players backing favourites achieve closer to target RTP)

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Source: Game Concept Document

“At install-time the operator sets the target RTP they desire Hedge’Em to run at.”
“The target RTP is set by the operator at installation time but the actual RTP can be influenced by other configuration parameters such as ‘Rounding Algorithms’ and player gameplay strategy.”
“As with other table games such as Blackjack, how a player plays Hedge’Em will affect the RTP.”

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Operator Configuration

RTP is a per-installation configuration parameter, not a per-session or per-player setting:
ConfigTypeDefaultRange
targetRTPnumberTBDOperator-defined (regulatory limits apply)
The RTP parameter drives houseMargin during server-side game record generation. Once generated, game records encode the margin implicitly in oddsActual values.

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JavaScript Reference

JS Source: Margin applied server-side during game generation. Client reads odds_actual and odds_rounded from pre-generated game records. RTP margin is not recalculated in the client — it is baked into the data at generation time. Relevant field: gameName in coredata.ts (e.g. "Max RTP") reflects the RTP configuration used to generate the record.

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TypeScript Implementation

Current status: TS client consumes pre-computed odds from coredata.ts. RTP margin configuration is not yet wired in the TS standalone client — the coredata was generated with a specific margin applied at source. Full RTP configuration support is tracked in F032.

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Acceptance Criteria

#CriterionJSTSUMA
AC1payoutOdds = fairOdds × targetRTP for all hands⬜⬜⬜
AC2Changing targetRTP updates all computed odds⬜⬜⬜
AC3gameName in coredata reflects the RTP configuration usedN/A✅N/A

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Version Parity

VersionStatusNotes
JS (reference)⬜ Not auditedMargin baked into server-generated game records
TS⬜ Not auditedReads margin-adjusted odds from coredata
UMA⬜ Not auditedPhase 5
  • F006 — Odds Calculation (full formula)
  • F032 — RTP Config (operator installation config)
  • F033 — Rounding Algorithms (post-margin rounding affects actual RTP)