What comes through the door, and what stops it

Open the equipment list Every door, window and defence device with hit points, damage, power a hit and whether zombies can walk past it.

A crisis sends the same 7 kinds with multipliers on them: on their damage, on their hit points, and for 4 of the scheduled hordes on their attack speed. The worst scheduled crisis in the game multiplies damage by 10, hit points by 2.5 and attack speed by 1.3. That is why a barrier that held one wave falls to the next: the kinds are the same, and everything about them is bigger.

The heaviest attacker is 500 hit points and 8 damage a hit. Under Enhanced Zombie Horde that becomes 26 damage a second from one zombie, with the attack-speed multiplier counted, and up to 40 on the field at once across the door and the window.

What you are facing

The spread is narrow apart from one outlier. Most are 80 to 120 hit points and 1 damage a hit; the Zombie (Mutant) has 500 hit points and 8 damage, and it is the only one of them that walks slower than 1.5, at 1.

The game’s files carry 2 further kinds that no scheduled crisis sends: Crawler and Climber. They are in the tables with full stats, and nothing on the calendar draws on them, so nothing on this page counts them.

What the crisis does to them

Open the crises list The whole crisis calendar: every horde, cold wave, rain, mold, rat infestation and outbreak with its days, and every wave a horde sends.

A zombie that does 2 damage a hit does 20 under Enhanced Zombie Horde. Nothing about your barrier changed between those two waves; the arithmetic on the other side did. Plan the wall for the multiplier you expect, not the one you have survived.

What stops them

Mechanical Chainsaw Mechanical Chainsaw Package Furniture Packages 3000 g 3×3 cells Keeps indefinitely Mechanical Chainsaws that can be installed at defensive positions. is the damage. At 24 a second across 4 targets it outputs 9× what anything else does. It is also the only one zombies walk straight past rather than having to break, so it thins a wave without slowing it.

Electric Trap Electric Trap Package Furniture Packages 3000 g 3×3 cells Keeps indefinitely Electric Traps that can be installed at defensive positions. is not about damage. Its 2.67 a second is negligible; what it does is take 50% off the speed of up to 4 zombies for 5 seconds. Everything behind it gets that time.

Spike Barrier Spike Barrier Package Furniture Packages 3000 g 3×3 cells Keeps indefinitely Spike Barriers that can be installed at defensive positions. costs no power at all and deals 15 back to whatever bites it. On a wave of 80-hit-point zombies that is 6 bites to kill one for free, which is the whole case for it when the generator is already loaded.

Sandbags Sandbag Package Furniture Packages 3000 g 3×3 cells Keeps indefinitely Sandbags that can be installed at defensive positions. , wall, and nothing else. At 600 hit points the piece carries 3× the hit points of the other slot pieces and deals nothing back, which is exactly what you want standing in front of them.

Where they come from

No shop sells any of the four. Each is a workbench recipe in its Defenses tab, with no Crafting level needed, made from the scrap the shops sell at $10 a piece; the two powered devices wait on the Defence level that unlocks their recipe. Money spent on a horde goes on the door, the window and the generator, and the devices come out of the scrap bag.

What to craft has the workbench itself and the rest of the bench.

Power is the real limit

The heavy device is also the more efficient one per point of damage, so the reason to run the lighter one is the slow, not the power bill. Either way both stop when the power does, read what it takes to keep the lights on before you build a defence that depends on a generator, and check the draw of everything else in the equipment list.

You can choose to bring them

Everything above happens on the schedule. Three items let you decide instead.

You throw one out through a door or a window. None of them is for sale: they turn up while you are out scavenging, so the choice is what to do with one you found rather than whether to buy it.

The reason to want a pack at a time of your choosing is that everything else about a horde is fixed. You know the schedule, so you can meet a pack with full doors, a charged battery and a working trap line, instead of meeting the next scheduled one halfway through a repair.

A lured horde is a crisis like the others, with its own multiplier: the lured hordes come at ×3, ×7, ×10 damage by the size of the crowd, and the largest matches Enhanced Zombie Horde, the hardest scheduled crisis, at ×10, with up to 44 on the field. Each holds the openings for 24 hours.

The reason not to is in the third row. The largest draws the largest crowd there is, and nothing about that is reversible once it is thrown.

The state that tells you it is going badly

The game raises a state called Tense when the way in is close to failing, and its wording is the clearest instruction in the game: "The doors and windows won't hold much longer! Nothing else matters—hold the house first."

Take it literally. Everything on this page is worth doing before that appears and worth abandoning after, because a barrier that falls costs more than anything you were going to do with the time.

Levelling Defence

Defence levels buy the devices: the first powered one at level 3, the second at level 4. The levels also promise rows of slots to put them in, and that half is the game’s own wording rather than something the tables carry: the ring is one flat count of 592 places with no level attached to any part of it, so this site cannot tell you which rows a level opens or whether it opens any.

What to do

1. Put Sandbags Sandbag Package Furniture Packages 3000 g 3×3 cells Keeps indefinitely Sandbags that can be installed at defensive positions. in front of anything that fights. It has 3× the hit points of the devices and no other job.
2. Fit Spike Barrier Spike Barrier Package Furniture Packages 3000 g 3×3 cells Keeps indefinitely Spike Barriers that can be installed at defensive positions. while you have no power to spare. It costs nothing to run and kills the weakest zombies in 6 bites.
3. Add Electric Trap Electric Trap Package Furniture Packages 3000 g 3×3 cells Keeps indefinitely Electric Traps that can be installed at defensive positions. for the slow, not the damage, 50% for 5 seconds on 4 zombies is worth more than its 2.67 damage a second.
4. Save Mechanical Chainsaw Mechanical Chainsaw Package Furniture Packages 3000 g 3×3 cells Keeps indefinitely Mechanical Chainsaws that can be installed at defensive positions. for when the generator can carry it. It is the damage, but zombies walk past it, so it needs something behind it that blocks.
5. Judge the wall by the multiplier, not the last wave. The hardest scheduled crisis multiplies damage by 10, and the barrier you fit has to hold against that.

Quick reference

• Toughest zombie: 500 hit points, 8 damage, speed 1.
• Hardest crisis: Enhanced Zombie Horde, ×10 damage, 40 at once, day 75.
• Horde days: 7, 14, 15, 34, 49, 61, 75, 95; the first is Zombie Siege on day 7.
• Most damage: Mechanical Chainsaw, 24 a second across 4, but they walk past it.
• Best slow: Electric Trap, 50% for 5s.
• No power needed: Spike Barrier (15 back per bite) and Sandbags.
• Not for sale: every device is a workbench recipe, $30 to $40 of scrap each.
• Devices come from Defence levels. The slots are one flat ring of 592 places and no table ties a row of it to a level.