Game Relationships

Games do not exist in isolation. An expansion extends a base game. A reimplementation shares mechanics with its predecessor. A big-box edition contains multiple products. The GameRelationship entity captures these connections as typed, directed edges.

GameRelationship Entity

Field	Type	Required	Description
`id`	UUIDv7	yes	Primary identifier
`source_game_id`	UUIDv7	yes	The game this relationship originates from
`target_game_id`	UUIDv7	yes	The game this relationship points to
`relationship_type`	enum	yes	The type of relationship (see below)
`ordinal`	integer	no	Ordering hint for display (e.g., expansion release order)

Relationship Types

Type	Direction	Description	Example
`expands`	expansion -> base	Source adds content to target; source requires target to play	Wingspan: European Expansion `expands` Wingspan
`reimplements`	new -> old	Source is a new version of target with mechanical changes	Brass: Birmingham `reimplements` Brass
`contains`	collection -> item	Source physically includes target (big-box, compilation)	Dominion: Big Box `contains` Dominion and Dominion: Intrigue
`requires`	dependent -> dependency	Source cannot be used without target (stronger than `expands`)	7 Wonders: Cities Anniversary Pack `requires` both 7 Wonders and 7 Wonders: Cities
`recommends`	game -> game	Source suggests target as a companion (non-binding)	A solo variant fan expansion `recommends` the base game’s organizer insert
`integrates_with`	game <-> game	Source and target can be combined for a unified experience	Star Realms `integrates_with` Star Realms: Colony Wars

Directionality

All relationships are stored as directed edges from source_game_id to target_game_id. For symmetric relationships like integrates_with, both directions are stored:

Star Realms -> integrates_with -> Star Realms: Colony Wars
Star Realms: Colony Wars -> integrates_with -> Star Realms

This allows querying from either side without special-casing.

Case Study: The Spirit Island Family Tree

Spirit Island is an excellent example of the relationship model’s expressiveness. It has standard expansions, a standalone expansion, and dependency chains:

flowchart TD
    SI["Spirit Island<br/><i>base_game</i>"]

    BC["Branch & Claw<br/><i>expansion</i>"]
    JE["Jagged Earth<br/><i>expansion</i>"]
    NI["Nature Incarnate<br/><i>expansion</i>"]
    HSI["Horizons of Spirit Island<br/><i>standalone_expansion</i>"]

    P1["Promo Pack 1<br/><i>promo</i>"]
    P2["Promo Pack 2<br/><i>promo</i>"]
    FF["Feather & Flame<br/><i>compilation</i>"]

    BC -->|expands| SI
    JE -->|expands| SI
    NI -->|expands| SI
    P1 -->|expands| SI
    P2 -->|expands| SI
    FF -->|expands| SI
    FF -->|contains| P1
    FF -->|contains| P2

    HSI -.->|integrates_with| SI

    style SI fill:#1976d2,color:#fff
    style HSI fill:#7b1fa2,color:#fff
    style BC fill:#388e3c,color:#fff
    style JE fill:#388e3c,color:#fff
    style NI fill:#388e3c,color:#fff
    style P1 fill:#f57c00,color:#fff
    style P2 fill:#f57c00,color:#fff
    style FF fill:#e65100,color:#fff

Key observations from this graph:

Branch & Claw, Jagged Earth, and Nature Incarnate are expansion type games with expands relationships pointing to Spirit Island. They require the base game.
Horizons of Spirit Island is a standalone_expansion. It has an integrates_with relationship to Spirit Island (bidirectional) but does not have an expands relationship, because it does not require the base game.
Promo Packs are promo type games with expands relationships. They add individual spirits or scenarios. Feather & Flame is a compilation that contains both Promo Pack 1 and Promo Pack 2 – the individual packs were difficult to obtain, so they were re-released as a single product. It also expands Spirit Island directly.

Querying Relationships

Get all expansions for a game

GET /games/spirit-island/relationships?type=expands&direction=inbound

Returns all games where target_game_id is Spirit Island and relationship_type is expands – i.e., everything that expands Spirit Island.

{
  "data": [
    {
      "source_game_id": "01912f4c-7e3a-7b1a-8c5d-9f0e1a2b3c4d",
      "target_game_id": "01912f4c-8a2b-7c3d-9e4f-0a1b2c3d4e5f",
      "relationship_type": "expands",
      "metadata": {
        "adds_spirits": 2,
        "adds_power_cards": 22
      },
      "_links": {
        "source": { "href": "/games/spirit-island", "title": "Spirit Island" },
        "target": { "href": "/games/spirit-island-branch-and-claw", "title": "Spirit Island: Branch & Claw" }
      }
    },
    {
      "source_game_id": "01912f4c-7e3a-7b1a-8c5d-9f0e1a2b3c4d",
      "target_game_id": "01912f4c-9b3c-7d4e-af5a-1b2c3d4e5f6a",
      "relationship_type": "expands",
      "metadata": {
        "adds_spirits": 10,
        "adds_power_cards": 52
      },
      "_links": {
        "source": { "href": "/games/spirit-island", "title": "Spirit Island" },
        "target": { "href": "/games/spirit-island-jagged-earth", "title": "Spirit Island: Jagged Earth" }
      }
    },
    // ... Nature Incarnate, Promo Pack 1, Promo Pack 2, Feather & Flame
  ],
  "_links": {
    "self": { "href": "/games/spirit-island/relationships?type=expands&direction=inbound" }
  }
}

Get the full family tree

GET /games/spirit-island/relationships?depth=2

Returns all relationships within 2 hops of Spirit Island, enabling reconstruction of the full family graph.

{
  "data": [
    {
      "source_game_id": "01912f4c-7e3a-7b1a-8c5d-9f0e1a2b3c4d",
      "target_game_id": "01912f4c-8a2b-7c3d-9e4f-0a1b2c3d4e5f",
      "relationship_type": "expands",
      "_links": {
        "source": { "href": "/games/spirit-island", "title": "Spirit Island" },
        "target": { "href": "/games/spirit-island-branch-and-claw", "title": "Spirit Island: Branch & Claw" }
      }
    },
    // ... other expands relationships ...
    {
      "source_game_id": "01912f4c-7e3a-7b1a-8c5d-9f0e1a2b3c4d",
      "target_game_id": "01912f4c-bd5e-7f6a-cb7c-3d4e5f6a7b8c",
      "relationship_type": "integrates_with",
      "_links": {
        "source": { "href": "/games/spirit-island", "title": "Spirit Island" },
        "target": { "href": "/games/horizons-of-spirit-island", "title": "Horizons of Spirit Island" }
      }
    },
    {
      "source_game_id": "01912f4c-ea8b-7c9d-fe0f-6a7b8c9d0e1f",
      "target_game_id": "01912f4c-ce6f-7a7b-dc8d-4e5f6a7b8c9d",
      "relationship_type": "contains",
      "_links": {
        "source": { "href": "/games/spirit-island-feather-and-flame", "title": "Spirit Island: Feather & Flame" },
        "target": { "href": "/games/spirit-island-promo-pack-1", "title": "Spirit Island: Promo Pack 1" }
      }
    },
    // ... depth=2 traversal includes relationships of related games
  ],
  "_links": {
    "self": { "href": "/games/spirit-island/relationships?depth=2" }
  }
}

Get what a game requires

GET /games/spirit-island-branch-and-claw/relationships?type=expands&direction=outbound

Returns the single relationship: Branch & Claw expands Spirit Island.

{
  "data": [
    {
      "source_game_id": "01912f4c-8a2b-7c3d-9e4f-0a1b2c3d4e5f",
      "target_game_id": "01912f4c-7e3a-7b1a-8c5d-9f0e1a2b3c4d",
      "relationship_type": "expands",
      "metadata": {
        "adds_spirits": 2,
        "adds_power_cards": 22
      },
      "_links": {
        "source": { "href": "/games/spirit-island-branch-and-claw", "title": "Spirit Island: Branch & Claw" },
        "target": { "href": "/games/spirit-island", "title": "Spirit Island" }
      }
    }
  ],
  "_links": {
    "self": { "href": "/games/spirit-island-branch-and-claw/relationships?type=expands&direction=outbound" }
  }
}

Case Study: Brass Reimplementations

Reimplementation captures when a game is rebuilt with significant changes but shares a lineage. The Brass family spans nearly two decades:

flowchart LR
    B["Brass<br/><i>(2007)</i>"]
    AI["Age of Industry<br/><i>(2010)</i>"]
    BL["Brass: Lancashire<br/><i>(2018)</i>"]
    BB["Brass: Birmingham<br/><i>(2018)</i>"]
    BP["Brass: Pittsburgh<br/><i>(2026)</i>"]

    AI -->|reimplements| B
    BL -->|reimplements| B
    BB -->|reimplements| B
    BP -.->|reimplements| B

    style B fill:#757575,color:#fff
    style AI fill:#43a047,color:#fff
    style BL fill:#1976d2,color:#fff
    style BB fill:#1976d2,color:#fff
    style BP fill:#1976d2,stroke-dasharray: 5 5

Key observations from this graph:

Brass (2007) – Martin Wallace’s original design, set in Lancashire during the Industrial Revolution. All subsequent entries reimplement this game.
Age of Industry (2010) – Wallace’s own abstracted reimplementation with variable maps, predating the 2018 relaunch. A distinct design direction (green) from the later Roxley series.
Brass: Lancashire (2018) – a refined re-release of the original Brass by Roxley Games. Same Lancashire setting, updated rules and art. Despite sharing a setting with the 2007 original, it is a distinct game entry with a reimplements relationship.
Brass: Birmingham (2018) – a new map with distinct economic strategies, also by Roxley. Paired with Lancashire as the 2018 relaunch.
Brass: Pittsburgh (2026) – upcoming entry in the Roxley series (dashed arrow indicates unreleased).

All five are distinct games linked by reimplements, capturing mechanical lineage without implying compatibility or dependency.

Why not treat these as versions of one game? On BoardGameGeek, the original Brass (2007) has no separate entry – it exists only as a “Version” under Brass: Lancashire. This collapses a meaningful design distinction: the 2007 and 2018 games have different rules, different component sets, and different ratings communities. OpenTabletop models them as separate game entities connected by reimplements, preserving the historical lineage while keeping each game’s data (ratings, polls, weight) independent.

OpenTabletop Documentation