Lunar Red Alert — Space-Age RTS

Overview

Command & Conquer, in a vacuum

Lunar Red Alert keeps the fast, classic RTS gameplay of OpenRA’s Red Alert and moves the whole war to a cold, airless world. Every design decision follows one question: what changes when there’s no air and barely any gravity? Your infantry carry a finite air supply. Step outside a pressurised zone and the countdown begins. Artillery hangs in the low-gravity sky. Craters wall off the battlefield into natural chokepoints.

Built on a real engine

A total conversion of OpenRA — the mature, open-source C#/.NET remake of the Westwood RTS engine. Not a mock-up: real traits, real YAML, real gameplay.

Two ways to play

The full OpenRA conversion is a desktop game (Win/Linux/macOS). A separate web-native prototype — same lunar mechanics, built for the browser — is playable right here, no install.

Free & open (GPLv3)

Evolved from OpenRA and released under the same GNU GPLv3. You can read, build, modify and share every line.

Environment

Four rules of a lunar battlefield

◉ Oxygen, not fuel

Every soldier carries an air tank that drains tick-by-tick in vacuum and refills inside a pressurised bubble. An empty tank grants a “suffocating” state the rest of the game reacts to.

☠ Vacuum damage

Out of air and out of shelter, a unit takes periodic vacuum damage until it either reaches pressure or dies. Vehicles are sealed and immune.

↧ Low gravity

Infantry bound at ~140% speed in 1/6 g; vehicles handle differently; arcing shells travel farther and hang longer. Gravity is a single world-level value (Moon 16% · Mars 38%).

⌂ Pressurised domes

Your base structures project a life-support field. Inside it, troops breathe and heal their air; push the front line forward by building outward.

How the systems chain together

Structure

A base building projects pressurised to nearby units

→

Oxygen

Refills while pressurised, else drains; empty → grants no-oxygen

→

Vacuum

If exposed & out of air → periodic damage

→

Movement

Low-g speed boost; suffocating units slow to half

Look & feel

Procedurally-generated lunar terrain

These are real outputs from the mod’s asset tools — not concept art. The Phase 3 generator bakes a cohesive, seamlessly-tiling lunar tile set (regolith, basalt, ice, crater floor & cliffs) in a unified palette.

A composed lunar battlefield: regolith plains, dark basalt patches, cyan ice deposits and crater clusters, assembled from real game tiles — **Lunar battlefield** — the actual Phase 3 tiles (`tools/gen_lunar_terrain.py`) composed into a map region: regolith plains, dark **basalt** flats, cyan ice deposits (the resource), and walled **crater** clusters. Engine-style variant rotation breaks grid repetition.

Labelled set of seamless lunar terrain tiles — **The tile set** — regolith ×3, basalt, ice, crater floor & cliff. Torus-periodic noise = no seams when tiled.

Color-coded crater-field skirmish map: grey plains, dark craters, cyan ice, spawn pads — **Crater-field map** — a `gen_map.py` layout: plains, walled craters, ice, and corner spawn pads.

ℹ️These tiles are shipped as real, loaded OpenRA tilesets (lunar.yaml/mars.yaml) and are what the browser alpha actually renders in a live skirmish — not just standalone art. No in-page gameplay screenshots here yet; go play the real thing above instead.

Under the hood

What’s actually in the repo

The mechanics are implemented as real OpenRA engine traits (C#) plus a lightweight data-only mod. Nothing here is placeholder.

Engine traits OpenRA.Mods.Common

Oxygen.cs — air supply
DamagedByVacuum.cs — hazard
GravitySpeedModifier.cs — low-g
OxygenBar.cs — O₂ meter
LowGravity.cs — world gravity

The mod mods/spaceage

mod.yaml — manifest
spaceage-defaults.yaml — traits
spaceage-structures.yaml — domes
tools/gen_*.py — asset gen
SPACE-AGE-DESIGN.md — full plan

A soldier’s vacuum survival, in engine terms — a trait that damages exposed, airless units, modelled on OpenRA’s own DamagedByTerrain:

// fires every DamageInterval ticks while a unit is exposed and out of air
void ITick.Tick(Actor self)
{
    if (safe) { ticks = 0; return; }              // under a dome / sealed hull
    if (Info.RequireOxygenDepleted && oxygen?.Current > 0) { ticks = 0; return; }
    if (--ticks <= 0) {
        ticks = Info.DamageInterval;
        self.InflictDamage(self.World.WorldActor, new Damage(Info.Damage, Info.DamageTypes));
    }
}

Play it

Build & run (desktop)

The game is a desktop OpenRA mod, so “playing” means building the engine once on a machine with the .NET SDK. First launch downloads the Red Alert content it reuses.

# 1. get the code
git clone https://github.com/dr-richard-barker/Lunar_Red_Alert.git
cd Lunar_Red_Alert

# 2. build the engine + lint the mod
make
./utility.sh spaceage --check-yaml

# 3. launch the Space-Age mod
./launch-game.sh Game.Mod=spaceage

Once in a skirmish: build a base, send infantry into the open and watch the O₂ bar drain, then pull them back under the dome to refill. Full verification checklist is in SPACE-AGE-README.md.

Roadmap

Where it’s going

PHASE 1

Core physics hooks Done

World-level low gravity + low-g movement traits. No changes to the engine core.

PHASE 2

Oxygen & vacuum survival Done

Air supply, vacuum damage, pressurised domes, the O₂ meter — all wired onto RA units.

PHASE 3

Lunar visuals & terrain In progress

A seamless-tiling terrain generator (regolith, basalt, ice, crater floor & cliffs) in a unified lunar palette is done and shipped as real in-game tilesets — see the gallery above. Remaining: crater-rim transition tiles, ice as the harvestable resource, and cold-palette/black-sky lighting.

PHASE W

Real engine in your browser Done

The actual OpenRA engine — not a rebuild — compiled to WebAssembly and running live from this GitHub Pages site, no download required. Play it now; full status log in WASM-PORT-PLAN.md.

PHASE 4

Compile, package & release Planned

Build on a .NET machine, verify the checklist, then package desktop installers for Windows / Linux / macOS.