Object Model

All game resources exist both in-game and on-chain. This section explains how in-game items are deterministically mapped to Sui objects.

Items

Every in-game resource is represented as an item with two key identifiers:

• item_id — unique identifier for the item in-game

• type_id — identifier for the item type (e.g., fuel type, assembly type)

A singleton item is uniquely identified by item_id + tenant. A non-singleton item is uniquely identified by type_id + tenant.

tenant distinguishes different game server instances (e.g., production, testnet, development).

Deterministic ID Derivation

On-chain object IDs are derived deterministically from the in-game identifiers using Sui's derived objects. This ensures a 1:1 mapping between in-game items and on-chain objects.

The derivation key is a TenantItemId:

public struct TenantItemId has copy, drop, store {
    item_id: u64,
    tenant: String,
}

A single shared ObjectRegistry is used to derive all object IDs. Every game asset : characters, assemblies, network nodes derives its object ID from this registry using the same TenantItemId key. This guarantees that each in-game item ID can only be used once across all object types.

public struct ObjectRegistry has key {
    id: UID,
}

When creating an object (e.g., a Character), the ID is derived from the registry:

let character_key = in_game_id::create_key(game_character_id as u64, tenant);
let character_uid = derived_object::claim(registry.borrow_registry_id(), character_key);

Since the derivation is deterministic, the object ID can be pre-computed off-chain using the registry's object ID and the TenantItemId.

Shared Objects

Most on-chain objects (characters, assemblies, network nodes) are shared objects. This allows both the game server (admin) and the character owner to mutate the same object without ownership transfers.

Reference:

• object_registry.move

• in_game_id.move