Iron Curtain — Platform Capabilities

Everything you get when you choose Iron Curtain as your RTS platform — whether you’re a player, a modder, a map maker, or building a total conversion.

For Players

Gameplay Modes

The Red Alert Experience — Faithful and Enhanced

IC recreates the Red Alert feel using values verified against EA source code, then adds quality-of-life features that don’t break the classic identity:

Faithfully Recreated:

• Palette-indexed sprite rendering with all original SHP draw modes (shadow, ghost, predator)
• Isometric 14-layer Z-order (terrain → shadows → buildings → units → aircraft → projectiles → effects → UI)
• Credit counter with ticking animation, power bar with green/yellow/red states
• EVA voice system with priority queuing (rare notifications don’t get lost)
• Unit voice pools with no-immediate-repeat selection
• Dynamic music (combat/build/victory transitions honoring Frank Klepacki’s intent)

IC Enhancements (New Features With No Classic RA Equivalent):

• Attack-move (default on), rally points, parallel factories, unit stances (Aggressive/Defensive/Hold/Return Fire)
• Smart box-select (harvesters deprioritized), camera bookmarks (F5-F8)
• Dynamic weather system affecting movement and terrain passability (D022)
• Veterancy promotions with visible rank indicators and stat bonuses
• Render mode toggle (F1): Classic / HD / 3D — switchable mid-game (D048)

Customization — Play Your Way

IC doesn’t force one way to play. Every axis is independently composable:

Balance Presets (D019):

• Classic (original EA values — frozen, never changes)
• OpenRA (tracks upstream OpenRA balance patches)
• Remastered Collection
• IC Default (patched once per ranked season based on telemetry)
• Custom (player-editable YAML)

Subfaction Selection (proposed — under research):

• Allies pick a nation — England, France, Germany, Greece — each with a thematic passive and one tech tree modification reflecting their alternate-timeline military tradition
• Soviets pick an institution — Red Army, NKVD, GRU, Soviet Science Bureau — competing power structures within the totalitarian state, each with a distinct playstyle identity
• Narrative asymmetry (countries vs. institutions) with mechanical symmetry (both sides get 1 passive + 1 tech tree mod) — reasonable balance overhead
• Classic preset uses original RA1 country bonuses (5 countries, 10% passives); IC Default uses the expanded 4×4 system; Custom/modded subfactions via YAML inheritance
• Community can add new countries or institutions via Tier 1 YAML modding (no code required)
• See research/subfaction-country-system-study.md for full design rationale and industry research. Requires D019 integration and community feedback before formal adoption

Experience Profiles (D033):

• Vanilla RA, OpenRA, Remastered, or Iron Curtain — each bundles balance + theme + QoL + AI + pathfinding + render mode
• Override any individual axis in the lobby
• Create and share custom profiles via Workshop

Quality of Life Toggles (D033):

• Production: attack-move, waypoint queue, multi-queue, rally points, parallel factories
• Commands: force-fire, force-move, guard, scatter, unit stances
• UI: health bars, range circles, build radius, target lines, selection outline
• Selection: box shape (diamond/rectangle), smart type cycling
• All individually toggleable, not locked to presets

Pathfinding Variants (D045):

• Remastered (original feel), OpenRA (improved A*), IC Default (flowfield + ORCA-lite hybrid)
• Per-lobby selection, mod-extensible via WASM

AI Personality & Difficulty (D043):

• Named AI Commanders with portraits, specializations, visible agendas, and contextual taunts (Generals ZH / Civ 5 pattern)
• 6 built-in RA1 commanders (Col. Volkov — Armor, Cmdr. Nadia — Intel, Gen. Kukov — Brute Force, Cdr. Stavros — Air, Col. von Esling — Defense, Lt. Tanya — Spec Ops)
• Two-axis tuning: commander persona (aggression, expansion, tech preference) × engine difficulty scaling (resource bonuses)
• Mix different commanders in the same match — each AI slot picks independently
• Puppet Master strategic guidance: optional external advisor (LLM, human coach, or future types) that directs AI objectives without replacing tick-level control; Masterless by default
• Community commanders via Workshop (YAML — no code required); LLM-generated commanders (Phase 7)
• Replay-based behavioral mimicry: AI learns from your replays (D042)

Multiplayer Infrastructure

• Relay servers eliminate lag-switching and host advantage — relay owns the clock (D007)
• Sub-tick fairness — orders from faster and slower players processed fairly (D008)
• Adaptive run-ahead — client predicts during lag, corrects without rubber-banding
• Encrypted transport — X25519 key exchange, AES-256-GCM authenticated encryption, Ed25519 identity binding (TransportCrypto)
• Community servers — single ic-server binary with toggleable capability flags (relay, matchmaking, ranking, Workshop P2P seeding, moderation) and federated trust (D074)
• Cross-engine browser — see OpenRA and CnCNet games from the IC client (D011)
• Portable identity — 24-word recovery phrase; restore on any machine (D061)

Replays & Analysis

• Auto-recording of all matches with Match ID system
• Arbitrary seeking (forward and backward) via keyframe re-simulation
• 5 camera modes: free, player perspective, follow unit, directed (AI auto-follows action), drone cinematic
• Observer overlays: army composition, production queues, economy, powers, score, APM
• Heatmaps: unit death, combat, camera attention, economy
• Graphs: army value, income, unspent resources, APM — all clickable (jump to that moment)
• Video export (WebM) with cinematic camera path editor, lens controls, letterbox
• Foreign replay import — play OpenRA .orarep and Remastered replays with divergence tracking (D056)
• Anonymization for sharing (strip names, voice, chat)

Workshop & Content

• Browse and install maps, mods, campaigns, themes, AI presets, music, sprites, voice packs, and more
• One-click mod profiles — save different mod combinations, switch instantly
• Auto-download on lobby join — missing content installs automatically (P2P preferred, HTTP fallback)
• Mod fingerprint — SHA-256 hash ensures all players have identical rules
• Federated mirrors — official server, community mirrors, local directories; works offline with bundles

Tutorial & Onboarding (D065)

• Commander School — 6-mission dopamine-first tutorial campaign (blow things up first, learn economy later)
• IC-aware hints — veterans see “IC adds rally points,” newcomers see “Right-click to set a rally point”
• Feature Smart Tips — non-intrusive contextual tips on Workshop, Settings, Profile, and Main Menu screens
• Adaptive pacing — hint frequency scales with demonstrated skill
• Post-game learning — “You had 15 idle harvester seconds” with replay moment links

Platform Support

For Modders & Content Creators

Three-Tier Modding System

Each tier is optional and sandboxed. No C# runtime. No engine recompilation. No forking.

OpenRA Compatibility — Bring Your Existing Work

Scenario Editor (SDK — D038)

A full visual mission editor inspired by OFP’s mission editor and Arma 3’s Eden Editor:

12 editing modes: Terrain (paint tiles/resources/cliffs/water), Entities (place units/buildings/props), Groups (squad organization), Triggers (area-based conditional logic), Waypoints (OFP F4-style visual route authoring), Connections (visual trigger/waypoint linking), Modules (30+ drag-and-drop logic blocks), Regions (named spatial zones), Layers (dynamic mission expansion), Portals (sub-map transitions), Scripts (Lua file browser/editor), Campaign (mission graph wiring)

Key capabilities:

• Simple/Advanced mode — same data model, different UI complexity; beginners place units in minutes, advanced users add triggers and scripting
• Entity placement with double-click, naming (variable names for scripts), faction assignment, probability of presence, condition of presence, veterancy, health, inline Lua init scripts
• Trigger system — area-based with conditions (unit present/destroyed/captured/built), min/mid/max randomized timers, repeatable/one-shot, Lua escape hatch for custom conditions
• Module system — 30+ pre-built logic nodes: Wave Spawner, Patrol Route, Guard Position, Reinforcements, Destroy Target, Capture Building, Defend Position, Escort Convoy, Weather Change, Camera Pan, Cinematic Sequence, Map Segment Unlock, Sub-Scenario Portal, Tutorial Step, Spectator Bookmark, and more
• Waypoints — visual route authoring with types (Move, Attack, Guard, Patrol, Harvest, Script, Wait), synchronization lines for multi-group coordination, route naming for script reference
• Mission outcomes — named outcome triggers (Mission.Complete("victory_bridge_intact")) wired to campaign branch graph
• Compositions — reusable prefabs (base layouts, defensive formations, scripted encounters) saved and shared via Workshop
• Preview / Test / Validate / Publish toolbar — Test launches real game runtime; Validate checks rules asynchronously; Publish Readiness aggregates all warnings
• Git-first collaboration — stable content IDs, canonical serialization, semantic diff/merge helpers
• Undo/redo + autosave with crash recovery
• Interactive guided tours — 10 built-in step-by-step walkthroughs with spotlight overlay and validation (D038)
• F1 context help — opens authoring manual page for any selected element

Asset Studio (SDK — D040)

XCC Mixer replacement with visual editing — no command-line tools needed:

• Browse .mix/.big/.oramap archives with extraction
• View sprites (.shp/.png with palette), palettes (.pal), terrain tiles (.tmp), audio (.aud/.wav/.ogg), video (.vqa/.mp4/.webm), 3D models (.gltf/.vxl)
• Edit palettes (remap, faction colors, hue shifts), sprite sheets (reorder frames, adjust timing, composite layers), terrain tiles (connectivity rules, transitions), chrome/themes (9-slice panels, live menu preview)
• Convert bidirectionally: SHP ↔ PNG, AUD ↔ WAV, VQA ↔ WebM
• Import PNG → palette-quantized SHP; GLTF → game models with LODs; fonts → bitmap sheets
• Batch operations — bulk palette remap, resize, re-export across assets
• Diff/compare — side-by-side version comparison with pixel-diff highlights
• Hot-reload bridge — edit assets, see changes in running game immediately
• Provenance metadata — track source, author, license, modification history per asset
• Optional LLM-assisted generation (Phase 7) — describe a unit → LLM generates sprite sheet → iterate

Campaign System (D021)

• Branching graph backbone — missions linked by named outcomes, not linear lists
• Optional strategic layer / War Table — phase-based campaign wrapper that presents operations, enemy initiatives, and urgency between milestone missions
• Operations as a distinct campaign tier — main missions, SpecOps, theater branches, generated operations, and follow-up reveals all use the same campaign graph foundation
• Expiring opportunities — optional mission nodes with expires_in_phases timers and on_expire consequences let the world move without you
• Arms race / tech ledger — campaign-visible acquisition / denial state that changes later missions and endgame composition
• Command Authority and phase pressure — players cannot run every operation before the main mission becomes urgent
• Multiple outcomes per mission — win/loss/partial each branch differently
• No mandatory game-over — designer controls what happens on defeat (retry, fallback, consequences)
• Unit roster persistence — surviving units carry forward with veterancy, kills, equipment
• Campaign variables — Lua-accessible flags, counters, and state that persist across missions; strategic-layer campaigns also get first-class phase / initiative / ledger state
• Hero progression (optional) — XP, levels, skill trees, loadouts per named character
• Intermission / War Table screens — Hero Sheets, Skill Choice, Armory/Loadout, operation cards, and strategic readouts between missions
• Campaign Graph Editor in SDK — visual node-and-edge editing, drag missions, label outcomes, author phase metadata, validate branches

Export to Other Engines (D066)

IC scenarios can be exported to other Red Alert implementations:

• Export-safe authoring mode — live fidelity indicators (green/yellow/red) per entity/trigger
• Pattern-based trigger downcompilation — Trigger.AfterDelay() → RA1 timed trigger, Trigger.OnKilled() → destroyed trigger, etc.
• Extensible export targets — community can add Tiberian Sun, RA2, Remastered via WASM plugins
• CLI export — ic export --target openra|ra1 mission.yaml -o ./output/

The vision: IC becomes the tool the C&C community uses to create content for any C&C engine, not just IC itself.

Workshop Distribution (D030)

• Publish maps, mods, campaigns, themes, AI presets, music, sprites, voice packs, script libraries, observer layouts, camera paths, LLM configs
• Versioning — semver with dependency ranges (Cargo-style); lockfile for reproducible installs
• Licensing — SPDX identifiers with ic mod audit for compatibility checking
• Channels — dev / beta / release with promotion between channels
• P2P distribution — BitTorrent/WebTorrent for large packages; HTTP fallback
• Community mirrors — run your own Workshop server; federation with official
• Offline bundles — export resources as portable archives for LAN parties
• CI/CD integration — headless publishing via scoped API tokens; tag-based automation
• CLI: ic mod install, ic mod update, ic mod tree, ic mod audit, ic mod publish

LLM-Powered Creator Tools (Optional — D016)

Built-in CPU models (Tier 1) run locally after a one-time download; no account or external service needed. External LLM providers (BYOLLM Tiers 2–4) unlock higher quality.

• Single mission generation — text prompt → terrain, objectives, AI behavior, triggers, briefing
• Campaign generation — text description → full branching multi-mission campaign
• Natural language intent — “Soviet campaign, disgraced colonel, Eastern Front” → pre-filled campaign parameters
• Replay-to-scenario extraction — convert replay into playable mission with optional LLM-generated narrative
• Player-aware generation — LLM reads your match history for personalized missions
• LLM Orchestrator AI — strategic wrapper around conventional AI; AI handles micro
• Skill Library (D057) — persistent store of verified LLM outputs; promotes quality over time

For Engine Developers & Researchers

Deterministic Simulation Core

• Fixed-point math only (i32/i64, scale 1024) — no floats in sim; identical results on all platforms
• No I/O in sim — pure state evolution; no file, network, or clock access
• No HashMap/HashSet — BTreeMap/BTreeSet/IndexMap only; deterministic iteration
• Snapshottable state — full game state serializable for replays, save/load, crash recovery, delta encoding (D010)
• External Sim API — ic-sim is a public library crate: new(), step(), inject_orders(), query_state(), snapshot(), restore()
• Use cases: AI bot tournaments, academic research, automated testing, replay analysis tools

Pluggable Architecture (14+ Trait Seams — D041)

Every major subsystem is abstracted behind a trait — swap algorithms without forking:

Multi-Game Engine

IC is not hardcoded for Red Alert. The GameModule trait defines everything game-specific:

• Components, systems, and scheduling
• Fog model, damage model, pathfinding
• AI defaults, order validation
• Each module (RA1, TD, RA2, D2K, custom) registers its own rules
• Same engine binary runs different games via module selection

Performance

• Render-sim split — simulation at 15 Hz, rendering at 60+ FPS with interpolation
• Zero-allocation hot paths — string interning, object pooling, pre-allocated buffers
• Delta encoding — property-level change tracking; baselines (Quake 3 pattern) reduce snapshot payloads ~90%
• Amortized staggered updates — fog, AI, and pathfinding spread across multiple ticks
• Multi-layer pathfinding — hierarchical sectors + JPS + flowfield + ORCA-lite avoidance
• GPU compatibility tiers — auto-detection; playable on 12-year-old hardware

Security & Anti-Cheat

• Relay time authority — server owns the clock; lag-switch impossible (D007)
• Deterministic order validation — all clients agree on accept/reject; cheated orders rejected identically (D012)
• Capability-based WASM sandbox — mods cannot access filesystem, network, or raw memory (D005)
• Signed replay hash chain — Ed25519 signing; tampering detected (D010)
• Mandatory transport encryption — AEAD on all network traffic
• Bounded reconciler corrections — state corrections validated before application

Observability

• Unified OTEL telemetry — client, relay, tracking, AI all emit structured events (D031)
• Desync diagnostics — Merkle tree pinpoints divergence to exact system/entity
• Background replay writer — crash-safe, zero frame-time impact
• Diagnostic overlay — FPS, latency, order rate, path cache stats in-game

Community Infrastructure

• Unified ic-server binary with independently toggleable capability flags: relay, matchmaking, ranking, Workshop P2P seeding, moderation (D074)
• Ed25519 signed credential records — portable reputation across communities
• Transparency logs — server publishes signed operation log for accountability
• Federated architecture — communities interoperate with official infrastructure
• Server configuration via server_config.toml with deployment guide (Chapter 15)

Quick Comparison