arkham.build is a web-based deckbuilder for Arkham Horror: The Card Game™.

arkham.build extends the arkhamdb deck schema with a few fields for additional functionality.

• meta.extra_deck: Parallel Jim's spirit deck. Format: comma-separated list of ids "id1,id2,id3".
• meta.attachments_{code}: cards that are attached to a specific setup deck, for example Joe Diamond or Stick to the Plan. Format: comma-separated list of ids "id1,id2,id2,id3".
• meta.card_pool: packs that can be used for this deck. Used for limited pool deckbuilding such as #campaign-playalong. Format: "<pack_code>,<pack_code>". For arkham.build, new format pack codes take precedence over old format. Cycles can be added as cycle:<cycle_code>.
• meta.card_pool_extension_{code}: Some cards can extend the card pool with choices. This tracks their selection state. Format: "card:<code>,card:<code>".
• meta.fan_made_content: Stores fan-made content (cards, packs, encounter sets) used in this deck. See here.
• meta.hidden_slots: When syncing decks with fan-made content to ArkhamDB, we need to extract the slot entries and investigator. This object holds this data so we can later re-apply it.
• meta.sealed_deck: card ids that are pickable for this deck. Used for sealed deckbuilding. Format: comma-separated list of id / quantity pairs in the format "id:2,id:1,...".
• meta.sealed_deck_name: name of the sealed deck definition used. format: string.
• meta.transform_into: code of the investigator that this deck's investigator has transformed into. I.e. 04244 for Body of a Yithian.
• meta.banner_url: URL to an image to be displayed as banner for the deck. Preferably aspect ratio 4:1.
• meta.intro_md: Short deck introduction that uses the same markdown format that description_md uses.
• meta.annotation_{code}: Annotation for a specific card that uses the same markdown format that description_md uses. Annotations are not limited to cards in deck, but can also target cards in the side deck (upgrades, alternatives) or any card (reasoning for exclusion).

ArkhamDB imposes a strict limit on the amount of data that can be stored in the meta field of a deck. In order to work around this, we extract some of our custom metadata from deck.meta and store it in our own database before a deck is saved to ArkhamDB. The information is replaced with a token that can be used to retrieve it, the so called amk (additional metadata key). When a deck is fetched from ArkhamDB, our API consumes the entry and writes the actual metadata back to the deck.meta. The process is transparent to the API consumer.

The following fields are currently handled in this fashion:

• meta.annotation_{code}
• meta.fan_made_content
• meta.hidden_slots
• meta.intro_md
• meta.sealed_deck
• meta.sealed_deck_name

There is a public endpoint to resolve an amk via GET https://api.arkham.build/v1/public/additional_metadata/:amk.

The sealed deck feature expects a csv file in the format:

code,quantity
01039,2
01090,2
06197,2
07032,2

In this example, the sealed deck contains two copies of Deduction, Perception, Practice Makes Perfect and Promise of Power, so users would only be able to add these cards to their deck in the deck builder.