Forces

A force is the container an army is built from. The roster holds one or more forces, and every selection lives inside one:

Roster
└─ Force
   └─ Unit
      └─ ...

When starting a list, the player adds a force and picks the catalogue (faction) it draws from. Rules that need "which faction is this force" test the Primary Catalogue scope; see Scope & Context.

Force entries

Forces are defined as force entries, normally in the game system under Force Entries. Each force entry becomes a choice the player can add. A small game often has a single "Default Force"; games with detachments or allied contingents define several.

Forces can be shared and reused like selection entries: define a force under Shared Force Entries and point at it with a force entry link wherever it appears.

Categories make units available

A unit becomes selectable in a force through its category: link category entries into the force, and units whose primary category matches appear as choices under that slot. Constraints on the category link set the slot's minimum and maximum; see Army-wide limits. A category (or its link) can also carry a cost, and Show tracker keeps the slot visible with its count and limits even while empty.

What a force can carry

Besides category links and child forces, a force entry can have:

• Constraints: for example limiting how many of the force the roster may take.
• Costs: a price for taking the force itself.
• Readme: text shown to the player on the force, the place to explain how the detachment works and what it grants.
• Rules and profiles: info attached to the force is displayed with it.
• Modifiers: targeting its name, hidden flag, costs, constraints, readme, or error/warning/info messages.

Child forces

Forces can nest. A parent force can offer child forces: sub-forces or allied detachments with their own slots, nested under a parent force that carries whatever unites them. Age of Sigmar 4 and Horus Heresy 3 use this structure. The section label ("Child Forces") can be renamed on the force entry.

Child forces are one of the more complicated features. If a simpler structure (categories and constraints within a single force) expresses the rule, prefer that; for choices that unlock content without adding a whole force, see Sub-factions and allegiances.

Hiding child forces that don't belong

Force entries are defined once in the game system, so by default every faction's parent force offers every child force: pick one faction and you would still see the sub-forces belonging to all the others.

To make a child force appear only for its own faction:

1. Set the child force hidden by default.
2. Add a modifier that sets hidden to false, gated on an instance-of condition at Primary Catalogue scope matching that faction's catalogue; in words, "unhide when this force's selected catalogue is X".

If the same child force sits under more than one parent force, add a condition on the parent as well, so it only unhides in the right place.