Vault raids and defense

Vault raids are a planned v0.27 system in which automatic day-end incidents test the Vault’s defenses against an incoming intruder. The implemented development slice uses Exposure to change Raid Pressure, Raid Pressure to set the daily chance of an intrusion warning, and Security plus available defenders to determine whether the attacker is repelled or breaches the Vault.

Exposure and Raid Pressure

Exposure measures how much hostile attention the Vault currently attracts. Vault residents, restored electricity, an operational purifier, exposed infrastructure, and temporary raid effects can contribute to Exposure.

Raid Pressure is a separate saved value from 0 to 100. Exposure changes it once per day:

Exposure	Daily Raid Pressure change
0	-2
1 to 9	-1
10 to 14	No change
15 or more	floor(Exposure / 10)

Raid Pressure is a risk level, not a countdown. Reaching 100 does not guarantee an attack.

Raid Pressure	Status	Daily warning chance
0	Hidden	0%
1 to 24	Unnoticed	2%
25 to 49	Rumors	4%
50 to 74	Watched	7%
75 to 89	Targeted	10%
90 to 100	Priority Target	15%

The Central Atrium’s Operational Hub unlocks the Vault Status interface. This interface shows Exposure, Security, Raid Pressure, the current risk forecast, and the Vault’s automatic defense outlook.

Intrusion warnings

A successful daily roll schedules an intrusion instead of resolving it immediately. The day-end terminal reports signs of an intruder without revealing the attacker’s identity, objective, exact power, or exact arrival night.

The intrusion can arrive during either of the next two watched nights. There is a 70% chance that it arrives on the first watched night and a 30% chance that it arrives on the second. If the first night passes without contact, the warning becomes imminent for the final night.

Only one intrusion can be pending at a time. The warning and its fixed attacker data remain in the save until the raid resolves.

Automatic defense

Raid defense is calculated when the intrusion arrives. The calculation combines:

• Perimeter Security from powered infrastructure and defensive upgrades.
• The player’s current Strength, Combat, and Health.
• Each present resident who attends Vault Defense duty, using that resident’s Strength, Combat, and Health.

Vault Defense is an emergency assignment that can take effect on the same night. A resident must attend the assignment to contribute. Compliance affects whether the resident attends, but it is not applied a second time to the resident’s defense score.

The game compares total defense with the attacker’s power and assigns one of four outcomes: clean repulse, costly repulse, breach, or overrun.

v0.27 thief attacks

Natural attacks in the implemented v0.27 development slice are limited to the Thief tier. The three available thief profiles target different groups of common supplies:

Attacker	Preferred supplies
Scavenger	Water, then Toxwater
Drifter	Numb Agent, then Dust Rush, then Fury Shot
Courier	Stitch Kits, then Credits, then Scrap Metal

A thief’s carrying capacity starts at 20 Credits of item value, increases by 1 every two in-game days, and cannot exceed 200. The calculation uses each resource’s trade value and takes whole items. If preferred supplies are unavailable, the thief can select another eligible common resource.

Thieves can steal Credits, Water, Toxwater, Scrap Metal, Stitch Kits, Dust Rush, Fury Shot, or Numb Agent. They cannot steal weapons or progression resources such as Circuit Boards, Breach Charges, Water Filter Parts, and Training Gear Kits.

Thief attacks do not damage the player or residents, cause escapes, or award salvage. A successful defense prevents theft. The player gains Combat effort when they contributed defense (COMBAT EFFORT +10 on the compact card). Each attending Vault Defense worker gains +1 Combat, shown next to their name. A successful theft does not grant Combat progress. An intrusion can also resolve without a loss if no eligible supplies are available.

Raid recovery

After a thief attack resolves, Raid Pressure falls by 8. Raid Pressure growth and new attack rolls then pause for two days.

Driving a thief off grants Combat effort to the player (when they contributed defense) and +1 Combat to each attending Vault Defense worker. A successful theft grants none. Medical Duty support is part of the wider raid system, but the current natural Thief tier does not cause Health damage.

The day-end terminal records the result. A successful theft lists the resources that were removed. A repelled thief report confirms that no stores were lost, names posted defenders with their Combat gain, and shows player Combat effort when it applied.

v0.27 alpha scope

Scouts, Raiders, Warbands, and Mercenaries exist in the wider raid rules, but natural attacks in the v0.27 development slice are capped at the Thief tier. Higher-tier injuries, deaths, escapes, salvage, and temporary raid effects are not part of that natural raid pool.

The current preparation options are Vault Defense staffing and the Vault’s existing resource, utility, and upgrade state. Additional dedicated preparation choices remain planned for later development.

Exact values may change while the game is in alpha.

Related topics

• Vault management
• Combat system
• Time and calendar
• Development roadmap

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