Modelling a Gacha Box

    Modelling a Gacha Box

    This example is based on the mechanic of awarding winning players with Hextech Key Fragments and Hextech Chests, in Riot’s League of Legends.


    Remember to hit the PLAY button on the embedded diagrams throughout this article.

    Distribution of items based on designed drop rates.

    The player Opens 1 Hextech Chest. The player gets Rewards based on each item’s drop rates.

    • △ Sources produce Resources
      • The Source Opens Hextech Chest produces 1 opened chest each time it’s triggered
    • → Resource Connections transfer Resources
      • The amount of chests opened is set by the number 1 on the “get” Resource Connection
    • ◇ Gates distribute Resources
      • The dice symbol on the “Rewards” Gate denotes that the distribution is random
      • The chances for each type of drop are shown on the Formulas of the connections leaving the Gate
    • ◯ Pools collect Resources
      • Are used to keep track of the player’s items

    The following example sets the conditions needed for the player to reach the “open Chest” objective.

    The player wins a match. For each match won the player has the opportunity to get a Key Fragment, with a chance of 40%. If the conditions are met, a Key Fragment is awarded.

    Every time there are 3 Key Fragments available, the player forges 1 Key.

    • Converters transform one type of Resource into another
      • ▷ Forge transforms 3 Key Fragments into 1 Key
      • Note that the forge action happens AS SOON AS ALL Resources needed are available

    The player wins a match. For each match won the player gets a grade. If the grade is higher than -S (chance of that is 50%). If the condition is met, there’s a chance of 40% they receive a Chest.

    We’ll now tie these systems together.

    The △Open Hextech Chest becomes a▷Converter that uses 1 Key and 1 Chest to get Rewards.


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