Iron Curtain — Design Documentation

D021: Branching Campaign System & Strategic Layer

Decision Capsule (LLM/RAG Summary)

• Status: Accepted
• Phase: Phase 4 (campaign runtime + Lua Campaign global); campaign editor tool in Phase 6a
• Execution overlay mapping: M4.SCRIPT.LUA_RUNTIME (P-Core); campaign state machine is part of the Lua scripting layer
• Deferred features / extensions: Visual campaign editor (Phase 6a, D038), LLM-generated missions (Phase 7, D016)
• Deferral trigger: Respective milestone start
• Canonical for: Campaign graph structure, optional phase-based strategic layer (War Table), mission outcomes, persistent state carryover, unit roster, campaign strategic-layer state, Campaign Lua global
• Scope: ic-script (campaign runtime), modding/campaigns.md (full specification)
• Decision: IC campaigns are continuous, branching, and stateful. The base model is a directed graph of missions with persistent state, multiple outcomes per mission, and no mandatory game-over screen. Campaigns may also organize that graph into a phase-based strategic layer (War Table) between authored milestone missions. Operations, enemy initiatives, Requisition, Command Authority, and tech / arms-race ledgers are accepted D021 extensions, not separate experimental systems. Inspired by Operation Flashpoint: Cold War Crisis / Resistance and XCOM’s strategy layer. The full specification lives in modding/campaigns.md.
• Why:
  • OpenRA’s campaigns are disconnected standalone missions with no flow — a critical gap
  • Branching graphs with multiple outcomes per mission create emergent storytelling
  • Persistent state (unit roster, veterancy, flags) makes campaign progress feel consequential
  • “No game over” design eliminates frustrating mandatory restarts while preserving tension
• Non-goals: Replacing Lua mission scripting or forcing every campaign into a War Table model. Campaigns define the graph (which missions, what order, what carries forward); individual missions are still scripted in Lua (D024). The strategic layer is an accepted extension for campaigns that want phase-based operation planning, not a requirement for compact graph-only campaigns.
• Invariants preserved: Deterministic sim (campaign state is serializable, carried between missions as data). Replay-safe (campaign state snapshot included in replay metadata).
• Public interfaces / types / commands: Campaign (Lua global — D024), campaign YAML schema, CampaignState, CampaignFocusState, MissionOutcome, CampaignPhaseState, CampaignOperationState, GeneratedOperationState, EnemyInitiativeState, CampaignAssetLedgerState
• Affected docs: modding/campaigns.md (full specification), 04-MODDING.md § Campaigns, player-flow/single-player.md, research/strategic-campaign-layer-study.md
• Keywords: campaign, branching, mission graph, strategic layer, War Table, operation, enemy initiative, Command Authority, Requisition, arms race, outcome, persistent state, unit roster, veterancy, carryover, Operation Flashpoint, Campaign global

Core Principles

1. Campaign is a graph, not a list. Missions connect via named outcomes — branches, convergence points, optional paths.
2. Missions have multiple outcomes. “Won with bridge intact” and “Won but bridge destroyed” lead to different next missions.
3. Failure doesn’t end the campaign. A defeat outcome is another edge in the graph — branch to fallback, retry with fewer resources, or skip ahead with consequences.
4. State persists across missions. Surviving units, veterancy, captured equipment, story flags, resources carry forward per designer-configured carryover rules.
5. Continuous flow. Briefing → mission → debrief → next mission. No exit to menu between levels.
6. The graph remains authoritative. Even when a campaign uses a phase-based War Table, authored missions and operations still resolve through graph nodes and named outcomes.
7. Strategic-layer state is first-class. Campaign phases, Requisition, Command Authority, enemy initiatives, and arms-race ledgers are stored as structured campaign state, not just ad-hoc flags.

Campaign Graph (YAML excerpt)

campaign:
  id: allied_campaign
  start_mission: allied_01
  persistent_state:
    unit_roster: true
    veterancy: true
    resources: false
    equipment: true
    custom_flags: {}

  missions:
    allied_01:
      map: missions/allied-01
      outcomes:
        victory_bridge_intact:
          next: allied_02a
          state_effects:
            set_flag: { bridge_status: intact }
        victory_bridge_destroyed:
          next: allied_02b
        defeat:
          next: allied_01_fallback

Lua API (Campaign Global — D024)

-- Query campaign state
local roster = Campaign.get_roster()
local bridge = Campaign.get_flag("bridge_status")
local phase = Campaign.get_phase()
local chrono = Campaign.get_asset_state("chrono_tank")

-- Complete mission with a named outcome
Campaign.complete("victory_bridge_intact")

-- Modify persistent state
Campaign.set_flag("found_secret", true)
Campaign.add_to_roster(Actor.Create("tanya", pos))
Campaign.reveal_operation("ic_spy_network")
Campaign.mark_initiative_countered("chemical_weapons_deployment")

Strategic Layer Extension

For campaigns that want a between-mission command layer, D021 allows a phase-based strategic wrapper over the same graph:

• Campaign phases group operations and milestone missions into authored windows of opportunity
• Command Authority limits how many optional missions the player can run before the main mission becomes urgent, and Requisition funds them
• Enemy initiatives advance independently and resolve if not countered
• Asset / arms-race ledgers track what the player has acquired, what the enemy has deployed, and what has been denied, including quality/quantity variants

This is an extension of the graph model, not a replacement for it. A classic campaign can remain graph-only. An Enhanced Edition campaign can add a War Table without changing the deterministic mission / outcome foundation.

Full Specification

The complete campaign system design — including carryover rules, strategic-layer state, operation cards, hero progression, briefing/debrief flow, save integration, and the visual graph structure — is documented in modding/campaigns.md. That document is the canonical reference; this capsule provides the index entry and rationale summary.

Alternatives Considered