Defense in OGame does one thing above all else: it makes attacking you more expensive than it's worth. It will not stop a determined top-ranked attacker from crashing you, but a well-built defense layer forces every raider to run the numbers — and most of the time, those numbers won't add up in their favor. This guide walks you through every defense structure, explains the classic 30% rule, and gives you a practical framework for deciding how much defense your planet actually needs, including on the faster universes of OGames.
What Defense Can and Cannot Do
New players often build a handful of Rocket Launchers and assume they're safe. They're not — but understanding why reframes how you think about the entire mechanic.
Defense structures sit on your planet's surface and fight attackers in combat rounds, exactly like ships. They have hull, shields, and weapons. The critical difference from fleet: defense does not retreat. It fires every round until it's destroyed or the attacker leaves. That staying power matters more than raw damage output at lower counts.
What defense cannot do:
- Stop a sufficiently large fleet. Every defense has a breakpoint — enough Battleships and Bombers will grind through anything. Defense buys time and raises cost; it does not create a hard wall.
- Protect your fleet while it's sitting idle. If you leave your ships on the planet and someone sends enough firepower, both your defense and your fleet die. Defense and fleet-saving are complementary, not interchangeable.
- Prevent espionage. Spy probes bypass defense entirely. A raider will scout you before they send any real fleet, so defense only matters after the probe report is already in their hands.
What defense can do:
- Destroy or heavily damage attacking fleets, generating debris your recyclers can harvest.
- Make the profit margin negative for most mid-tier attackers.
- Buy you enough time to react if you have moon-based phalanx coverage. Learn more about watching incomings in our espionage basics guide.
- Rebuild after combat — a fraction of destroyed defense reconstructs for free each round (the rapid-fire rebuild mechanic in later OGame versions keeps this mechanic alive). On standard OGame-variant servers, a percentage of destroyed defense rebuilds automatically each wave.
The bottom line: think of defense as insurance. You pay a one-time resource cost, and it pays dividends every time a raider opens your probe report, does the math, and moves on.
The Full Defense Lineup Reviewed
OGame's defense tree runs from cheap disposable units to the massive plasma cannon that can one-shot a Cruiser. Each structure fills a specific role; mixing them correctly is what separates a good defense from a resource sink.
Rocket Launcher
The cheapest defense you can build. Rocket Launchers have poor shields but reasonable hull for their cost, and because they're so inexpensive you can build them in the hundreds early on. Their main job is volume — providing a large number of targets so heavier units like Battleships don't rapid-fire straight through to your resources. At high counts they also soak a huge amount of incoming fire before heavier structures take damage.
Light Laser
A modest step up with better shields. Light Lasers are usually skipped in high quantities once you have access to Heavy Lasers, but they're useful for filling out defense in the very early game when resources are tight. Don't over-invest here.
Heavy Laser
Noticeably stronger shields and weapon output than the Light Laser. Heavy Lasers are your first meaningful anti-raider unit — they threaten Light Fighters and can chip away at larger ships. Keep a healthy ratio alongside your Rocket Launchers as the baseline defense on every planet.
Gauss Cannon
High damage, high shields, moderate cost. The Gauss Cannon starts threatening Cruisers and above. It requires Weapons Technology 6, Energy Technology 6, and Shielding Technology 1, which puts it squarely in the mid-game. Once you can build them, they become a core element of any serious defense layer.
Ion Cannon
The Ion Cannon is controversial. Its damage output is low compared to its cost, but its extremely high shield value means it absorbs incoming shots without dying — protecting the units behind it. Some players swear by them as absorbers; others skip them entirely in favor of more Rocket Launchers. On speed universes where you have abundant resources, adding a moderate number can improve your defense's durability.
Plasma Turret
The crown jewel of planetary defense. Plasma Turrets deal massive damage per shot and can rapidly fire against large ships. They require Plasma Technology 7, making them a late-game investment, but a planet with even a modest count of Plasma Turrets becomes dramatically more expensive to crack. Prioritize these once your research allows it — they change the calculus for every attacker who probes you.
Shield Domes and Missile Silos
Two special structures sit outside the normal damage-and-shoot loop: the shield domes and the Interplanetary Missile Silo.
Small Shield Dome
You can only have one per planet, but that one unit absorbs a significant amount of incoming weapon fire before any other defense structure takes damage. Think of it as a sacrificial first layer — attackers have to burn through 2,000 shield points before touching anything else. Build it immediately; the cost is trivial relative to the protection it adds early on.
Large Shield Dome
Same concept, dramatically higher shield value. The Large Shield Dome absorbs 50,000 points of incoming fire. At the resource investment it requires, you want this on any planet that holds significant resources or serves as a forward base near active pvp space. It is one of the highest-efficiency defense investments in the game once you can afford it.
Interplanetary Missile Silo (and Anti-Ballistic Missiles)
The Missile Silo stores Interplanetary Missiles (IPMs) and Anti-Ballistic Missiles (ABMs). IPMs are an offensive tool — you can fire them at enemy defense structures from a safe distance without risking a ship. ABMs are the defensive counter: each one can intercept one incoming IPM. The rule of thumb is to keep twice as many ABMs as IPMs you expect an attacker to fire at you, since it takes two ABMs to intercept one IPM reliably.
IPM harassment is a legitimate early-to-mid game tactic on speed universes where research moves fast. Keeping at least a small ABM stockpile is cheap insurance against having your defense quietly shredded while you're offline.
How Much Defense Is Enough: The 30% Rule
The most cited rule in OGame defense planning is the 30% rule: your total defense firepower (measured in resource cost) should equal at least 30% of the resources sitting in your storage. The logic is simple — if cracking your defense costs more than 30% of what an attacker can steal, most of the time the attack is unprofitable.
Why 30% specifically? In a standard raid an attacker can steal up to 50% of your stored resources (capped by cargo capacity). If your defense destroys, say, 40% of a fleet worth 2× your stockpile in order to steal that 50%, the net math tips negative for them. The 30% threshold isn't a magic number — it's a practical heuristic that has held up across OGame's history because it accounts for the cost of fuel (deuterium) and the risk of losing ships in combat.
In practice, apply the 30% rule per planet, not globally. Your main planet likely holds more resources than a mining colony; its defense should be proportionally heavier. A distant colony that you regularly empty before logging off needs far less defense than one that accumulates resources for days.
Beyond the 30% threshold
Once you clear 30%, additional defense has diminishing returns unless you're building toward a specific breakpoint — for example, having enough Plasma Turrets that even a Battleship fleet takes unacceptable losses. Some experienced players invest far beyond 30% on key worlds because they want those planets to be essentially un-worthwhile to attack regardless of what the attacker brings. This is expensive and generally reserved for your home system or a heavily developed production planet.
The other side of the coin: never over-invest in defense at the expense of fleet. Ships generate income through raiding and resource transport. Static defense just sits there. Early in the game, every resource you spend on a Rocket Launcher is a resource not spent on a Large Cargo Ship that goes out and raids someone. Balance is everything — check our first ships guide for how to think about that early allocation.
Defense vs. Fleet Philosophy
There is a long-standing debate in OGame between "turtles" (players who pour resources into defense and rarely fleet-save) and "fleeter" playstyles. The reality in 2026 is that pure turtling has become less viable as offensive tools — especially IPMs and the Deathstar — have scaled up. A turtle with no fleet is a stationary resource dispenser for anyone with enough firepower.
The winning philosophy is layered protection:
- Fleet-save your ships when you go offline. This is non-negotiable. No defense compensates for leaving a large fleet on the ground while you sleep.
- Keep defense at or above the 30% threshold relative to your stored resources.
- Drain your silos regularly through spending, trading, or fleet-saving resources. An empty planet is worth zero to a raider regardless of its defense.
- Use moons for fleet saves and phalanx coverage. Defense is a supplement to active play, not a replacement for it.
Players who combine all four layers are genuinely difficult and expensive to harass. Players who rely on only one are vulnerable, no matter how many Plasma Turrets they build. For more on the early decision-making framework, see our first-week build order guide.
Defense on Speed Universes
Everything above applies universally, but speed universes change the math in important ways. On a standard 1× server, building your way to Plasma Turrets takes weeks or months. On OGames' three universes, that timeline collapses dramatically.
In Andromeda (50× economy, 100× research), you can reach Plasma Technology 7 and start placing Plasma Turrets within your first week of active play. The 5,000 Dark Matter sign-up bonus and 1,000 weekly DM keeps commander bonuses active, which speeds construction further. With a 43% ship debris rate, even a failed attack on your planet generates a debris field — which your recyclers can harvest to rebuild defense faster than the attacker expected.
In Nebula (99× economy, 198× research) and especially Proxima (200× economy, 400× research), research races ahead so quickly that Plasma Turrets become accessible in the first couple of days. Proxima's 80% ship debris rate is particularly punishing for attackers — crack someone's defense and you've handed them most of the fleet value back in debris. This creates a natural disincentive to attack well-defended targets that doesn't exist on slower servers.
Practical speed-universe adjustments:
- Front-load your defense early. Because everyone levels up fast, a player who ignores defense for the first few days is an easy target for someone who built Gauss Cannons on day two.
- Scale the 30% rule aggressively. On speed universes resources accumulate faster, meaning your stockpile grows quickly between logins. Your defense needs to keep pace.
- Build Large Shield Domes sooner. The resource cost is covered faster, and the protection it provides against early rushers is proportionally higher.
- Keep ABMs stocked. IPM harassment is common on speed servers because attackers can build their missile silos fast and fire them cheaply relative to the damage they do.
The high debris rates on all three OGames universes (up to 80%/32% for ships/defense on Proxima) mean that planetary defense is more self-reinforcing than on standard servers. Every attack that fails against your planet generates a field you can harvest. This creates compounding momentum: strong defense pays for more defense.
Choosing the right universe for your playstyle matters as much as the defense you build within it. Our universe comparison guide breaks down the tradeoffs between Andromeda, Nebula, and Proxima in detail.
FAQ
Does defense rebuild after a battle?
Yes, partially. A percentage of destroyed defense structures automatically reconstructs after each combat round without consuming additional resources. The exact rate depends on the server configuration, but this mechanic means your defense is never permanently reduced to zero from a single attack unless the attacker completely overwhelms you in every round. This also means that attacking a heavily defended planet with small waves — hoping to chip it down gradually — is an inefficient strategy for most attackers.
Should I build defense before I have ships?
Not as your primary focus. The first few days of OGame are about generating resources — mines, storage, energy, then the first production ships. A bare minimum of Rocket Launchers (a few hundred) is fine as early protection, but pouring resources into defense before you have a working economy and at least some Large Cargo Ships is a mistake. The raiding income those ships generate will far outpace what static defense protects. See our first planet guide for the correct early priorities.
Do weapon, shield, and armor upgrades apply to defense structures?
Yes — this is often overlooked by new players. Every level of Weapons Technology, Shielding Technology, and Armor Technology increases the output of every defense structure on every planet by the same percentage as it does your ships. A fully researched player's Rocket Launchers hit significantly harder than an unresearched player's identical structure count. Keep your combat research moving; it multiplies the value of all the defense you've already built.
Is it worth building Ion Cannons?
The Ion Cannon is the most debated structure in OGame's defense tree. Its damage output is low for the cost, but its shield absorption value is among the highest of any structure at its tier. It functions best as a frontline absorber — taking hits that would otherwise destroy more valuable units like Gauss Cannons or Plasma Turrets. On speed universes where resources flow quickly, adding a moderate number (perhaps 20–40% of your Rocket Launcher count) improves defense durability noticeably. On tighter economies, most experienced players prefer more Rocket Launchers or Gauss Cannons instead.
Can I use defense to farm debris off attackers?
Absolutely — and on OGames this is a real strategy. If your defense is strong enough to destroy or heavily damage an incoming fleet, that fleet generates a debris field in your planet's orbit. With Recyclers ready and a moon for Phalanx intelligence, you can harvest that debris and profit directly from failed attacks. The high debris rates on OGames universes make this more viable than on the official OGame servers: Andromeda returns 43% of ship value as debris, Nebula 55%, and Proxima a massive 80%. A planet with serious Plasma Turret coverage and Recyclers on standby can turn large attack waves into a resource windfall.
Ready to put these principles into practice? Register on OGames and pick the universe that fits your playstyle — whether you prefer the measured pace of Andromeda or the breakneck progression of Proxima, building a solid defense layer from day one is the fastest path to playing without fear.