institution/Wiki/contraband/Tunnels.md

Tunnels

The Prison-Architect dig: a disposed pawn goes down, not through — under the ground and everything built on it, out past the last wall you were relying on.

A locked door stops a prisoner who wants to walk out. It does nothing at all about a prisoner who digs. This is the escape that ignores your perimeter, because it does not cross it — it goes beneath it. It is slow, it is quiet, and it works for pawns who would never join a mood-driven riot.

The crude pick

The dig needs a tool. The crude pick is filed off the cell's own furniture exactly the way a shiv is — same disposition gate, same damage-to-furniture tell; see Improvised Weapons. Where the shiv is a weapon, this is a way out: it carries no combat stats and is never equipped.

Stat	Value
Description	"Useless as a weapon and useless above ground — but pointed downward, patiently, it is a way out that no lock and no guard can see."
Max HP	60
Mass	1.2 kg
Concealability	0.5
Hides	in cell only (too bulky to ride on a body)
Deteriorates	yes

Because it can only hide in the cell, a warden turning over the room can find the pick itself — and, far more easily, the hole it is digging.

A second secret riding on the first

A tunnel is "the third thing a contraband item can be, after 'made' and 'used in a break': a thing you dig your way OUT with, quietly, over days." It is deliberately not a job you can catch a pawn performing. There is no supervised task a warden could walk in on and interrupt — only a secret that grows and a wall that eventually gives. The dig advances on the same 250-tick heartbeat that makes contraband, so the same search that finds a shiv can find the tunnel.

The pick must first be made (or smuggled). Only once it is finished does the dig begin, as a second, longer secret carried on the same hidden pick.

Who digs

Digging gates on three things:

1. A person, and held — prisoner, slave, or ward patient.
2. The disposition to dig for weeks: a base chance of 0.08 — deliberately below the shiv's 0.10. "Fewer pawns will dig for weeks than will palm a shiv." It is a fixed fact about the pawn.
3. A viable plan exists — there has to be somewhere to surface (see below).

This is the entire reason tunnels live in Contraband and not in a prisoner-only escape mod:

It works for prisoners and ward patients alike. Prisoner Realism's escapes are for "mood prisoners" mid-break bashing a door, and a committed ward patient is never that pawn. A patient with a filed-down pick and the disposition to use it can still, slowly, dig out — and nothing else in the ecosystem lets them.

Planning the dig: aim for the wilderness

The target is not the cell wall. "You do not go through the wall, you go under it." The pawn aims for the nearest wilderness — the first standable spot, scanning outward up to 60 tiles, that opens onto the map edge and is not the room they are held in.

Two consequences fall straight out of that:

• Depth is your defence, and a single wall is not. A tunnel from a deep bunker is a long dig; a tunnel from a shack against the map edge is a short one. Wrapping one more wall around a cell does almost nothing — the dig already ignores intervening walls entirely.
• A fully enclosed, map-locked base with no reachable edge has nowhere to surface. The plan fails, no progress is made, and the tunnel stalls — progress is kept, not lost. Seal the map and the shaft simply waits.

How long

Dig time scales with how deep the cell sits — about 6 cells of depth per day, clamped between 3 and 15 days, and jittered ±25% each poll:

	Days
Minimum (shallow cell near the edge)	3
Maximum (deep bunker)	15
Per day of digging	~6 cells of depth

The floor of 3 days keeps even the shortest tunnel a real threat window you have time to catch; the ceiling of 15 keeps the deepest from being effectively forever.

The tell: spoil

A dig has to go somewhere, and the dirt is where you notice it. Each dig tick, about half the time, the pawn drops one tile of dirt filth where they are digging:

A dirt floor swallows it; a paved cell shows it — exactly where a player might notice.

It is cheap and occasional on purpose: enough that a paved cell slowly accumulates a suspicious mess, not so much that it spams filth or litters a clean cell every tick. If you floor your cells, spoil is a genuine visual cue that someone is digging.

Finding a tunnel in a search

A tunnel is "a second, far less hideable secret." The pick hides at concealability 0.5, but the shaft gives itself away in proportion to how far along it is. When a warden search reaches the cell, an extra find chance is added on top of the tool's normal find chance — scaling up to +0.40 at a nearly-finished tunnel.

So a routine cell toss that finds a shiv can also catch a dig in progress — "the same guard patrol that finds a shiv finds the hole" — and the deeper the shaft, the harder it is to miss. A foiled dig counts against the prisoner the same as one that ran: on discovery, their escape-attempt tally ticks up, which raises this pawn's future search priority sharply (a known tunneller is the prisoner a warden checks first — see Warden Search). The full find math is on the Warden Search page.

Breakout

When the dig finishes:

1. Re-plan the exit so it is correct even if the base changed during the weeks of digging.
2. Breach the outer wall or fence the tunnel comes up beside — the outermost impassable wall or fence between the cell and the surfacing point. It is destroyed, leaving a visible hole the colony must repair, and proof of how they got out. An open perimeter needs no breach.
3. Record the attempt — it happened whether or not they get clear of the map.
4. Surface beyond the perimeter. They dug all the way out, so they emerge outside, not in the yard, with a little spoil dirt to mark where they came up.
5. Hand off to vanilla. Now that they are loose and outside, the base game's prison-break flow — and anything layered on it, e.g. Prisoner Realism — takes it from there. A pawn already outside who no longer qualifies as an in-prison escapee simply flees on their own; the breach and the emergence are the real outcome regardless.

The player gets one message: "{pawn} has tunnelled out under the perimeter and escaped." The tunnel and the pick are spent together.

How to defend against it

Defence	Effect
Floor the cells	spoil dirt becomes visible; you can see a dig
Search known offenders	a logged escape attempt is the heaviest single term in search priority
Deny the pick's raw material	no workable furniture, no pick — same starve as the shiv
Depth	a deeper cell is a longer dig and a wider window to catch it
Seal the map	no reachable edge means the tunnel stalls indefinitely

Note what does not help much: adding perimeter walls. The dig goes under them and only breaches the last one on the way out.

Quick reference

Constant	Value	Meaning
Dig base chance	0.08	before nature × nurture; fixed per pawn
Wilderness search radius	60 tiles	how far out it looks for a surfacing point
Cells per day	6	dig speed vs. cell depth
Min / max dig time	3 / 15 days	clamps on depth ÷ 6
Spoil chance per dig tick	50%	one tile of dirt filth
Extra find chance	up to +0.40	scales with how far along the dig is
Pick concealability	0.5	in cell only
On discovery / breakout	escape attempt logged	counted either way

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Part of the Institution suite — Core · Contraband · Justice · Gangs, alongside Foul Play and Ward. Each stands alone; together they interlock.