Defense planning
Protect normal accumulation and production assets without mistaking a bunker for a fleetsave.
Evidence reviewed 9 November 2026. Read the linked reference for formulas, sources and version limits; current account settings remain the final check.
What this guide covers
- Set a defensive budget from your collection interval and realistic local threats.
- Choose units for a job instead of copying a universal defense ratio.
- Separate combat losses, repaired units and permanent attrition.
- Check missile protection, combat bonuses and debris settings before trusting a simulation.
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Make the routine raid unattractive
Defense should make attacks on the resources and ships you normally leave behind unattractive. It is not a substitute for fleetsaving. Start with the likely attacker, exposed value and the amount of permanent loss you can afford.
Read the universe before choosing a build
Debris rules, repair settings, fleet speeds and current bonuses change the value of the same defense. Write these assumptions beside the comparison. Advice from another universe can give the wrong answer even with an identical unit mix.
Give each part of the defense a job
Cheap targets, larger guns and shield domes serve different roles. Their useful mix depends on the attacking fleet, technologies and budgets. The detailed unit-role table supports a comparison, not a fixed defense ratio for every account.
Understand rapid fire before adding more fodder
Rapid fire can make a large number of cheap targets less protective than it looks. Test the actual attacker against the proposed mix. More fodder does not automatically improve the result when it gives the attacker favorable repeat shots.
Shields protect their own unit
Shields belong to individual units and interact with shot size and combat rules. Do not pool all shield values into a single barrier. The reference separates the published threshold rule from unresolved exact-equality behavior.
Count permanent losses after reconstruction
Winning a battle and preserving investment are different results. Count losses after the applicable rebuilding chance, while recognizing that expected repair is not a guaranteed outcome. Restored defenses must also face any following wave.
Protect the bunker from missile preparation
ABMs can intercept IPMs, but the reserve is consumed. Missile preparation can remove defenses permanently before a fleet arrives. Do not assume a guaranteed mixed-defense spillover order or that a large Silo alone means enough interception stock.
Use missile formulas as estimates, not launch guarantees
Weapons, Armour, interception and the selected defense target affect missile damage. Treat baseline formulas as estimates and validate the current launch. Range, travel time and damage are separate calculations.
Develop defense by measured need
Compare complete defense projects at a fixed resource budget, then build the smallest useful improvement. Include exposed resources, likely fleets and rebuilding reserves. A defense that wins an unrealistic test may still attract profitable routine raids.
Make the simulator answer the real question
Hold the attacker and budget constant, then vary uncertain technology, loot, debris recovery and repeated waves. Distinguish defender survival from attacker profitability. Record the assumptions and permanent losses rather than only a green victory result.
When an attack is already coming
Read the incoming mission, timing and available resources before acting. Protect movable value and coordinate privately where useful. Panic spending or a blind missile response can add cost without changing the actual threat.
Detailed reference
A reusable way to test a bunker without inventing a universal ratio.
Quick checks
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Sources & version context
Evidence reviewed 9 November 2026. Read the linked reference for formulas, sources and version limits; current account settings remain the final check. Planning workflows and examples are Skie guidance. Game rules and interface requirements should be checked against the linked references and your current account.
- Defense tutorial · official forum archive, 2019; reconstruction and basic roles ↗
- Defensive structures discussion · official forum, 2020 with later replies; contextual strategy, not a current balance table ↗
- RapidFire · official forum archive; use corrected explanation, not the obsolete full stat table ↗
- Formula Thread v3 · archival classic formulas, last substantive revision 2015 ↗
- How shields work · official forum archive, individual shielding and round regeneration ↗
- TrashSim developer's 1% correction · January 2020; historical equality-edge evidence ↗
- IPM guide · official forum archive, 2019; interception, silos and primary targets ↗
- IPM algorithm discussion · official forum, 2020; exact spillover order explicitly disputed ↗
- Universe settings · official US announcement; 2021 update specifies missile use of war speed ↗
- Player classes · official US guide; Ion Cannon rapid fire against Reaper ↗
- Version 7 initial changelog · historical PTS announcement of Bomber rapid-fire additions; not a complete current stat reference ↗
- Version 12 changelog · January 15, 2026 live large-combat and simulator fixes ↗
- TrashSim archive notice · Origin, May 2026; old tool recommendations can expire ↗
- Circular universe announcement · 10 February 2015; IPM wrap requires circular solar systems ↗
- Bomber rapid fire against Plasma · post-release community discussion, January 2023 ↗
