The wave

At every dusk a wave spawns and comes for the living. There is no separate battle screen: every body is on the map, using the same barricades and the same weapons you do. Later nights mix in infected with rules you can read before they reach the wall.

How many

Wave size follows a late-rising table scaled to the seats in the run. A run for two faces gets roughly half the numbers below; one for eight gets twice as many.

Each forecast freezes when it is published. A new seat raises later forecasts, but a death or an absence never lowers them, and the number already on screen never changes. Nobody is ever cheaper dead, absent or quiet.

Gathering half the district into your hold does not raise it either. The people you bring home are defenders, not a bill.

Those are forecast numbers. What actually spawns is the forecast minus half of the wave zombies still standing from previous nights, rounded down — so leftovers are a two-for-one discount rather than a free pass. The field on any given night is roughly the forecast plus half of what you failed to clear. Killing them permanently is the only thing that shrinks it.

What comes

Night 1 teaches the Shambler. Night 2 adds the fast, lightly built Runner. Night 3 adds the Riser, which stands again in 60–90 minutes unless somebody spends 2 AP finishing the body (1 AP with Butcher). Night 4 adds the 90 HP Bruiser, whose successful tear removes two barricade levels. Night 5 adds the Caller, which announces a small reinforcement group before it arrives. Nights 6 and 7 mix the lot across two approaches. Subject One leads the seventh wave at 120 HP.

Gunfire is still meant to be used. It is also heard: four shotgun reports, or equivalent pistol fire, can turn one additional mixed group toward the shooter. That escalation happens at most once per night and is announced on the wire; those bodies appear as arrivals in the report.

Where from

The forecast is rolled from the run's seed and published free in the day banner: an exact count and a compass face. They arrive at the map edge on that face, spread about four cells either side of whatever the district thinks is the heaviest concentration of living people, and land on the nearest street.

That "heaviest concentration" weighting only picks the spawn face and the wording of the forecast. It is not how they path.

What they walk towards

This is the part worth internalising. Every 10 minutes, every traveling wave zombie is re-pointed at whichever claim is nearest to it — or, if nobody has claimed anything, at the nearest living player. Not at the biggest group. Not at the loudest. The nearest.

Which means a second claim on the far side of the district is not a decoy, it is a second front. And it means anything you leave lying between the spawn face and your hold is something the wave walks past on its way to you.

At the wall

They tear down one barricade level per successful attempt, at roughly 40% a go at night; a Bruiser tears down two. A closed door goes at about 55%. Then they walk in. They only work on a section that has living people inside it — an empty room is not interesting to them.

None of that paragraph is wave-specific: it is how every zombie works on every door, in every mode. The wave is just the night the arithmetic gets tested.