A dropship descends towards a colony on an orange planet, with a rocket pad, a monorail and a ringed gas giant filling the sky.

Orbital contract network // Free download

Space Defense Engineer

Take the contract. Ride the dropship down. Build a colony's defences along the canyon and hold it against everything the raiders send.

Download free

For Windows, macOS and Android. Version 2.0.0.

The game

Your base is the battlefield.

A tower defence where every turret you place and every upgrade you buy visibly grows the colony around you.

The tactical view: towers on terraced ground around a winding canyon road, under attack.

Build along the canyon

Raiders follow the road to your HQ while aircraft fly straight at it. Place guns on the rims, take the high ground for extra range, and keep your power grid in the black, because an overloaded grid slows every gun you own.

A close view of the colony's white modules, joined by tunnels, with a dome and a landing pad.

Upgrades you can see

Each tier stacks a tower higher on stilts and modules. Drill crystal deposits for income, raise habitats that link up with tunnels, and watch a landing site turn into a town.

The HQ terminal in light grey and orange, with contracts on the left and your base floating in the centre.

Pick your next job

Every contract has its own planet, route, hazard and payout, and you can survey it before you sign. Bank your pay to grow your HQ, license new weapons and take on harder work.

Five worlds

No two contracts look alike.

Each planet has its own colours, sky, light and weather, on a battlefield generated fresh for every contract.

Arsenal

Eleven structures. Nine ways to lose a colony.

Six turrets and five support buildings to answer swarms, armour, shields, aircraft and bosses, plus an orbital strike and an EMP for when it all goes wrong.

Turrets

Pulse CannonAll-rounder

Reliable bolts against anything that moves or flies.

Twin RepeaterRapid fire

Shreds swarms and light craft. Armour blunts it.

Siege MortarSplash

Slow arcing shells that wreck ground formations.

Arc CoilChain, slow

Lightning that jumps between targets and bogs them down.

Missile BatteryAnti-air

Guided warheads with double damage against aircraft.

Rail LancePierce

A hypersonic slug through everything on the line.

The raiders

SkitterSwarm

Fast, fragile, and never alone.

BulwarkShielded

A regenerating shield. Don't let up.

GunshipAircraft

Ignores the road and knocks your structures offline.

Colossus ConvoyBoss

The last thing you see on a bad day.

Version 2.0.0

Download

Free, with no account and no ads. Your progress saves on your device.

Windows

Windows 10 or later, 64-bit, with a Vulkan graphics card.

Zip, 95 MB Download for Windows SHA-256 bcbda8e3e66164f582e069af932f966614e2e355e0abee66f35a234845493ce2

macOS

macOS 11 or later on Apple silicon, or 10.15 or later on Intel.

Zip, 117 MB Download for macOS SHA-256 a8e54df9ea1327892e5cf135560ad126007d9f1633d79358a78fe6ca961cf711

Android

Android 7 or later on a 64-bit phone with Vulkan. Plays by touch.

APK, 85 MB Download for Android SHA-256 d92c52d11e58a6724c01ab44a811210da02f4111c14a6e32bef1c2088473c7e8

Install

Windows: extract the whole zip and run Space Defense Engineer.exe, keeping the .pck file beside it. The build isn't code-signed, so if SmartScreen warns you, choose More info, then Run anyway.
macOS: extract the zip and open the app. It isn't notarized, so macOS refuses it the first time: choose Done, then System Settings > Privacy & Security > Open Anyway.
Android: download the APK on your phone and open it. Android asks you to allow installs from your browser the first time.

Controls

WASD, wheel	Pan and zoom
Q E	Orbit the camera
1-0, click	Pick and place a structure
U X T	Upgrade, sell, targeting
F G	Orbital strike, EMP
Space, Tab	Launch wave, game speed
Touch	Drag to pan, pinch to zoom, tap a card and drag it onto the ground