Raid Defense

Mechanics Guide — Remnants: Post-Collapse Idle Survival

Overview

Raids are timed assault events where groups of raiders attack your settlement's walls simultaneously. Each raid lasts 25–30 seconds depending on threat level — Strength 1 raids last 25 s; Strength 6 and above last 30 s. Raiders approach from up to four directions — North Wall, South Wall, East Gate, and West Flank. You assign garrison to each wall and intercept advancing raiders before they breach.

Raids start once your population reaches 10+. They are both a threat and an opportunity: successfully repelling a raid earns Caches and Influence. Losing a wall costs resources. Losing all walls is a severe penalty.

Raid Timing

Raid Strength

Raid strength scales from 1 to 10 based on your colony's progression — shelter level and total scrap accumulated drive the formula. Higher strength means more raiders, faster advance speed, and harder surges.

• Strength 1–2: Single-wall raid. Manageable with basic defense.
• Strength 3–6: Two-wall raid. Garrison must begin to split.
• Strength 7+: Three-wall raid. Full defensive buildout required.
• Strength 8+: Pressure-3 siege attacks begin. Maximum aggression.
• Strength 10: Peak difficulty. Full five-building defense recommended.

Walls & HP

Each of the four walls has a base HP. Raiders drain it continuously during the assault. Perimeter Walls add a percentage damage resistance that applies to all walls.

• Perimeter Wall: +10% damage resistance per wall, max +50% at 5 walls. Applies globally to all four sides.
• Wall HP drains faster during surges.
• Garrison assignment reduces drain — more fighters on a wall = slower HP loss.
• A wall at 0 HP triggers breach unless Recapture is active.

Garrison Assignment

Your garrison pool is a percentage of total population, set by Guard Barracks. During a raid, you assign this pool across the active walls using sliders or the AUTO-BALANCE button.

• Base garrison pool: 25% of population.
• Guard Barracks: +10% per building, up to 75% of population at 5 barracks.
• Unassigned garrison does nothing — distribute fully.
• AUTO-BALANCE distributes evenly across all attacked walls instantly.
• Manual assignment lets you weight heavier toward the wall taking most fire.

Surge Attacks

Surges are intensified assault bursts that trigger during the raid. A surge targets a single wall with increased damage multiplier and faster raider advance. Surge warning: "⚡ BREACHING CHARGE — [WALL NAME]!"

• First surge typically triggers at 8–12 seconds into the raid.
• Subsequent surges cycle every 10–15 seconds.
• Surge damage is ×1.5 base, reduced by Floodlights.
• Floodlights: −8% surge damage per building, max −50% at 5 buildings. Lvl 3+ can trigger raider retreat during final assaults.
• When a surge warning fires, immediately shift garrison majority to that wall.

Breach & Recapture

When a wall's HP reaches zero it is breached. You have a 12-second recapture window to reassign garrison to that wall and restore it. If recapture fails, the breach resolves and resources are lost.

• Medic Station enables the Recapture mechanic. Without it, a breach immediately resolves.
• Medic Station also reduces breach losses by −15% per building (max −60% at 4).
• During recapture: pull garrison from stable walls and dump into the breached wall.
• If all four walls breach simultaneously, the penalty is severe — resources, morale hit.

Defense Buildings

Recommended Build Order

1. Watchtowers ×5 — interval extension is highest ROI in the entire Defense panel.
2. Perimeter Walls ×3–4 — base damage resistance before raids get strong.
3. Guard Barracks ×2–3 — garrison pool expansion.
4. Medic Station ×2 — recapture + loss reduction. Critical before strength 5+.
5. Floodlights ×3 — surge protection for deep runs.
6. Armory ×2 — late game, counter-raid delay is powerful.

Raid Rewards

Successfully repelling a raid (all walls hold) earns:

• Salvage Caches — condensed resource packs (Scrap, Food, Water mix).
• Influence — your reputation grows when word spreads that your settlement held.

Reward quantity scales with raid strength — a strength-8 repel is substantially more valuable than a strength-2. High-strength raids become net positive for your economy once your defense is solid.

Strategy

• Don't build offense before defense. Watchtowers first, always. Every Defense panel building should be started before hitting Shelter level 3.
• Watch raid strength, not just timing. Strength jumps as you progress. A comfortable Str-3 defense can be overwhelmed by Str-6 with the same buildings.
• Never be at 0 garrison when raid starts. The raid timer is visible in the Defense panel. Know when it's coming.
• Armory Lvl 2 Counter-Raid Sortie delays the next raid after every repel. Late game this can compound — two sorties in a row pushes the next raid back significantly.
• Population balance matters. Sending 80% of population on an expedition then getting raided = catastrophic. Keep at least 40% home during raids.
• Floodlights pay off at Lvl 3. The raider retreat mechanic at Lvl 3 can end raids early. A cheap win condition at high strength.

Infiltrators

Infiltrators are enemy scavengers that slip into your settlement between raids. They quietly drain your resources each tick until you manually repel them. Unlike raids, they give no warning — the Defense panel badge pulses when one is active.

• Spawn rate: Every 3–8 minutes once the Defense panel is unlocked. Up to 3 active simultaneously.
• Drain rate: Each infiltrator drains 3% of your current production rate per tick across all active resources.
• Repel reward: Clicking the Repel button recovers 1.15× all drained resources plus a bonus equal to ~30 seconds of scrap production.
• Counters: Floodlights and Guard Barracks reduce infiltrator spawn chance. Higher levels of each building push spawn intervals longer.