Infection Free Zone: The Ultimate Rebuilding Guide

This emergency guide has been written for all Operators around the world as part of the contingency operation IFZ. Though the world at large is rapidly falling to the infected, we have worked with experts to collate all the information required for building and managing successful safe zones, and – eventually – rebuilding society in the event of total global collapse. This information is spread into a number of sections covering different areas you’ll be challenged to face. Your mission is critical, so study careful.

(This guide will be a work in progress as the game goes through updates and Early Access, and as we learn more specifics on how the game mechanics work. Please comment if you have anything that can be added or needs to be corrected. Any information in particular need of additions or testing will be pointed out in brackets)

It’s important to pick a good spot for your bunker, and eventual safe zone:

• More built up areas (cities, large towns) will have more infected to deal with – dependant on the setting chosen in game set up – but more buildings and thus more supplies. Inversely, smaller areas may not have enough buildings or supplies to get by. This is shown, using the “Highlight playable tile” option, as either blank (too sparse), yellow (high population) or green (just right)
  
• You’ll need a variety of supplies to survive and thrive, so make sure local areas have the variety of buildings (food, tools, security supplies, etc.) you’ll need. Each square seems to be around 1 square kilometer, so you can use other tools like Google Maps to look for good locations and then find them in game (as the in-game map loads somewhat slowly and buggily)
• Make sure there are appropriate buildings close by: this is one the most important points. Your HQ should ideally be in a small building, with a variety of small to large buildings around it. This is because the HQ is severely limited in how much space it takes up at game start (to prevent super easy starts with a tonne of shelter and storage space), and you’ll want smaller buildings to start your zone with decent options to expand to. If there aren’t enough close by, you could have to grow your zone very large quickly, just to get set up, and then struggle with defence (see Buildings section for more)
• Infected are seen to have an incredible ability to swim; even zones on islands or mostly surrounded by water are likely to fall under attack from the water. However, bridges or thin spits of land can act as effective bottle necks, and swimming will slow the infected down to be more easily picked off from a distance (when the water is not frozen over)

Weather & Time
The seasons will pass and the weather will change from hot to cold and back, and in addition the times of sunrise and sunset will also change. This is critical, as the infected are averse to sunlight. They will hide during the day, and come out at night – this naturally makes days safer, and nights more hazardous, with some exceptions.

• Heavy storms can give enough cloud cover to let the infected step outside during the day
• On the clearest nights, the reflected light of a full moon can cause the infected to continue hiding, giving you a reprieve – though they tend to come back twice as hard the next night.
• As winter sets in, the shorter days will mean less sunlight for your workers, and the lower temperatures will reduce the effectiveness of your farms. It can also cause water to freeze, allowing fast movement over rivers and lakes; for both survivors, and the infected.
• (Currently temperature doesn’t affect survivors – no heating needed, squads don’t get cold)
• (Location on the world doesn’t seem to affect the changing of the seasons, or the climate of the map – zones in the far north/south have the same lengths as those on the equator. This needs testing)

Time also passes in the game specifically; each day lasts a month (and so a year lasts 12 days). As such winter might sneak up on you, so make sure to prepare for the cold.

Fog of War
You’ll only be able to see a small area around your zone, specifically around your squads, workers, and owned buildings. Squads will be critical to explore the region around your new zone, for locating useful supplies, vehicles, groups of survivors – and for spotting infected. Sometimes a heads up of incoming swarms will be the difference between fighting them off successfully, or falling to the horde.

Expeditions
The area around your zone will be made up of 9 map squares, with your HQ (and most of your zone) inside the central square. This main area is where buildings, NPC, infected etc. will spawn and where you can scavenge/fight in view. Beyond this is the rest of the region around your area, which can be accessed by squads to gather supplies without the micromanagement of choosing individual buildings, and can be done by zooming out enough to see the map view.

Squads can sometimes face infected or hostiles in these expedition zones, and so need to be kept an eye on. They can only be directed to leave that square, not micromanaged in combat.

Adapting
Your relatively small zone won’t have the heavy equipment or supplies for new construction, and so will have to rely on adapting existing buildings to suit their needs. Many of these will require you to find equipment (exploration locked) or rediscover lost techniques (research locked).

There are a number of different adaptations you can make:

• Headquarters: this is where your zone is commanded from, squads are created, and houses a few people and can store some resources. Extra HQs can be set up, which can work well as forward bases for scavenging/dismantling
• Warehouse: stores resources, fairly cheap to build, and is where workers will bring and pick up resources
• Shelter: a basic home for survivors, enough to keep people content (as long as there’s enough room)
• House: a more advanced, comfortable home with creature comforts. More expensive, but makes people very happy (research locked)
• Field: requires open space instead of a building, produces food but has lower effectiveness in the winter and cold months (exploration locked)
• Barn: keeps animals for raising, producing meat and fertilizer (exploration locked)
• Cookhouse: turns grain or meat into food rations, using wood as a fuel source
• Cannery: turns food rations from the cookhouse into canned food (research locked)
• Tool factory: uses wood and metal to create tools (research locked)
• Arms factory: uses wood and metal to create weapons (research locked)
• Chemical factory: creates fertilizer out of wood/fuel, and fuel out of wood/fetilizer (research locked)
• Walls: impassable structures to block infected reaching your buildings, with gates to allow survivors and vehicles to pass through (some research locked)
• Towers: fortified fighting positions to defend against infected (some research locked)
• Antenna: used to invite other survivors to your Zone, and recall all squads to base with one click (research locked)
• Medbay: heals squad members (when staffed, only during working hours) and produces medkits (research locked)
• Research centre: used to study, and generate, research materials which unlock (rediscover) new buildings and increase effectiveness (exploration locked)
• Weather centre: forecasts the weather over the coming days/months (research locked)
• Mast: a decoration to show off the power of your mighty zone (social media thing required)

Building Characteristics
Buildings come in many varieties, shapes and sizes, from small houses or sheds to massive superstores or skyscrapers, which are displayed in the game:

• Height: taller buildings allow squads to shoot over smaller buildings or walls, giving clear lines of sight for ranged attacks
• Surface: the surface area the building takes up
• Volume: easy maths, this is the height multiplied by the surface, and determines how much the building costs to adapt, the space you will have when adapted (and thus how many workers can be assigned, and how quickly it will produce), and how many resources it will give if dismantled.
• Name: the game takes data about what the building was before the infection, which can determine what loot spawns there, and help with roleplaying purposes

There are some important tips to consider:

• Damaged buildings can be repaired, the repair cost being based on the original cost multiplied by how damaged the building is. E.g. if a building is at 75% health, it will cost 25% of the original costs to repair *(clarification needed)
• Buildings have set hit points – this means a large building will take the same amount of damage as a small one, but will cost significantly more to repair because of how the costs are calculated
• For the most part, when buildings are being repaired they stop functioning; warehouses lose storage space, towers don’t attack, shelter/houses lose their capacity, etc.
• Bigger buildings are harder to defend as there is more area for the infected to attack. As the range on squads is calculated from the centre of the building, they may not even be able to hit infected outside if the building is large enough

Buildings can be partially adapted to still get some use out of them, without the higher costs – this is handy in a pinch, but it’s less efficient as the un-adapted part can’t be used for anything else, so you’re losing either productive space or the resources from a building that could be dismantled (where a smaller building could be used)

Dismantling
The main way to get resources for adapting and production is from dismantling old buildings. Not all buildings in your area will be useful; some are too small, some are too large, some could be cleared to prevent nesting places for the infected or make clear lines of sight for defence. Just remember, the further they are from your zone, the further workers will have to travel to bring the recovered resources back (more on that later)

This table will list the different buildings, their hit points, costs, and (where applicable) workers accepted. Area is given in cubic meters, but the conversion to imperial is to multiply by 1.308. Resources are abbreviated as W (wood), M (metal), B (brick), and BT (basic tool).

Types of Resources
A successful zone will rely on a variety of different supplies, that fall into different categories.

FOOD

• Crates of Canned Food: found by scavenging, or made using the cannery building to save food for later dates
• Food Rations: made in cookhouses, and eaten first if available
• Bag of Grain: made by farms, and rarely found while scavenging (which unlocks farms if playing story mode), used by cookhouses to make rations
• Raw Meat: made by barns, used by cookhouses to make rations at a greater efficiency than grain

Each crate of cans/food ration feeds 4 people for 1 day. Currently, food rations don’t expire OR provide extra happiness over canned food, so the main benefit is turning them into canned food (which takes 2 rations + 1 metal to give 3 canned food, giving a 50% gain albeit while using a non renewable but abundant resource)

CONSTRUCTION MATERIALS
Various supplies used in adapting or constructing buildings, making repairs, and as raw resources for production buildings.

• Wood: one of the most vital resources in the game, as it’s used to cook food as well as consruct most buildings. Harvestable from trees using workers, and by dismantling buildings
• Raw Metal: used for advanced production and buildings, harvested from scrap in the streets (car wrecks, streetlights) and dismantling buildings
• Bricks: abundant building material, but very useful for strong walls. Harvested from building ruins, and by dismantling buildings
• Basic tools: used for your fields and most factories. Found semi-rarely in scavenging, and made in the tool factory using metal and wood

WEAPONS & AMMO
Arguably some of your most vital supplies to survive the infected and hostiles

• Ammo: needed to supplies your squads, towers and gates that use firearms, each unit of 1 ammo is 100 rounds (a gate holding 300 ammo will take 3 units to resupply).
• Pistols; fairly weak, but also commonly found in scavenging, beating hostile humans, and made in the weapons factory.
• Assault Rifle: more rare, scavenged in security buildings and rarely from some hostiles, and made in the weapons factory.
• Shotgun: short range and best for fighting inside buildings, this can only be made in the weapons factory.
• Sniper Rifle: long range and high damage, this can only be made in the weapons factory.

See the Combat section for more details on using weapons, and their pros and cons.

EQUIPMENT & MISC
Lastly, the odd bits that make up the rest of your general supplies.

• Fuel: vital to run your vehicles, can be found by scavenging buildings or emptying vehicles found in your area. Can also be made in the chemical factory, from either wood or fertilizer (and used to make these resources)
• Fertilizer: a multi-use optional resources, produced by barns or from chemical factories using fuel or wood. Can be used to boost field production, make ammo (tool factory), or make fuel (chemical factory)
• Medkit: used directly, and only, by squads, this can be done manually by dragging a medkit on to a squad member’s picture, and is used automatically if they drop below 30% health (according to the tool tip – I haven’t seen this happen yet, possible bug). Found in scavening, and produced by medbays when not healing squads.

Production
Naturally, not everything you need will just be sitting in some house waiting for your scavenger teams, and even for some of the things that are, there won’t be enough. You’ll need to start producing supplies yourself inside your zone. Below are a few tables of all current production orders in the game, and base figures:

* Figure needs confirming

* Figure needs confirming

The time taken to complete a production cycle is (mostly) dependant on how many people are working in that building. This scales very simply, as the time taken to produce the resource is inverseley proportional to the number of people working on it. Put simply: doubling the amount of people, halves the work time:
1 worker : 40 hours > 2 workers : 20 hours > 4 workers : 10 hours > 8 workers : 5 hours etc.
Eventually you get marginal returns, so it ends up being better to have multiple of the same building rather than 1 super building with the same amount of workers.

Tips

• Efficiency is affected by mood; the best way to maximise production is keep everyone in houses, as this makes them happy and gives a flat 40% boost to ALL production. Can’t stress enough, this is huge
• The number of people that can be assigned to a building depends on it’s size. Bigger buildings = more people = faster production. Only the fields are set at 2 people max
• Speaking of fields, their efficiency will also be affected by temperature, dropping by 80% in winter – this is mitigated to 40% drop if everyone is kept happy (their positive attitudes thaw the fields)
• Production time is specifically when people are working; a rifle that needs 24 hours to be built will take 3 days (assuming 8 working hours per day). Workers only come out during the day for safety,
• Workers take precious time to walk to their workplace, so fields and factories should have homes nearby to get the most productive time out of workers – and don’t have water between them, as workers will path straight through water and not across bridges/around the water

Given the details in the above section you can work out what number of workers and resources you need for production of certain things, but I’ve taken the liberty of detailing two example food production chains for a zone of 100 survivors – one for grain rations, one for meat rations – since there’s multiple steps and factors that complicate it. You can then multiply this for the number of survivors you have

Each different option presumes base level production efficiency (no bonus or malus), and 8 working hours a day. Exact maths gives fractions of production cycles, so these have been rounded up to leave some margin for extra production.

GRAIN

MEAT

• As you can see, the most efficient method is using a Meat production chain with fertilizer, as this gives a net gain in fertilizer which can be used for fuel and ammo production, and uses the minimum number of workers (26 to feed 100) – but is the most complex
• Efficiency will drop during winter as the fields produce more slowly, but with the 40% boost for happiness (from building Houses) and the margins for extra production, it’s very easy to quickly build up a surplus of food

Shout out to Raven’s guide on food production calculations that helped to lay out this example.

You’ll start with a group of people who have managed to hide and survive with you (exact amount depending on the option chosen at game setup). These people make up your squads and workers, and could just be the future of humanity. However, you’re likely (and hopefully) not the only people still around by the time the all clear is given, and you’ll need help to grow your zone and rebuild society. One positive is that anyone still alive with be immune.

Squads
These are micro-managed groups of up to 4 people, who carry weapons and each have 1 inventory slot – a squad of 4 will have 4 slots. They are sent to scavenge in buildings for supplies, but also scout out the what’s left of the world around your zone. Since they’ll likely run into infected, they also equip weapons, depending on what you’ve got available. If you have no firearms, squads will have melee weapons by default, but this means they’ll be fighting infected hand-to-hand – a poor choice (see the Combat section for further details).

Workers
These are the macro-managed people that make up most of the population of your zone. You’ll see them walking around, and each person has unique pictures and names (based on the location of your zone).

Workers don’t go out at night; it simply isn’t safe enough for non-combatants. When resting (or not working, if unassigned) they will rest in shelters/homes/HQ.

Migrants/survivors
There will be neutral “squads” moving around the map identified by yellow markers, scavenging for supplies to get by, hiding in buildings at night, and occasionally fighting with the infected. If a squad or normal workers get close to neutrals (or if the neutrals approach one of your buildings), they’ll likely ask if they can join your zone. They can be accepted to increase your workpool or turned away, if you don’t have room. Sometimes they may just want to do their own thing, and patrol around by themselves.

It’s also possible to transmit invitations for your zone out to anyone listening, using an antenna (once researched and built). Sometimes people that hear this transmission will just head toward your zone, sometimes they’ll have a radio to answer and identify themselves, and you can ask them questions. This includes how many there are, and how they’ve survived (this currently always gives the same answer, and doesn’t idenfity whether they are “good” or “bad” – all survivors that answer are good and don’t betray or attack, yet). You can then offer to have them wait so you can send an escort squad to help them reach your zone, or tell them to make their way to you by themselves.

(Note: as far as can be seen, neutral survivors don’t actually consume resources across the map.)

Raiders/hostiles
There will always be those that don’t get along with, and with no central order or authority it’s likely you’ll come across hostile groups ready to attack your squads or zone.

These people can be even more dangerous than infected, as they could use ranged weapons – however, their numbers are likely to be limited. Furthermore, if beaten in combat, they will drop ammunition and weapons that can be used.

The Military
It’s likely that other organised groups will survive, including the national military. It’s impossible to say what chain of command will still exist by the time of all the clear, but any military presence will be well armed and armoured.

You’ll eventually get a transmission from a military commander, who will ask for some help as part of the story quests. This includes asking for supplies and people, and in return can be called upon to help fight infected – though they won’t always be available. You can also be antagonistic toward them, and refuse to help out.

(More details to be added about military interactions/story)

It’s a harsh fact of life; without order and society, there will be violence. There’s the infected to worry about, of course, but also wild animals, and hostile survivors or raiders. In this section I’ll list details of how to fight effectively, as well as different tactics to keep your squads alive.

For clarity, squads will refer to the survivors you control directly, and workers will refer to workers that are manning defense structures (towers and gates). Non-combatant workers don’t fight or defend themselves, so are left out of most of this information.

Squads are put together in HQ buildings

• The max number of squads seems to be dependant on either population size, land area on the map, or a combination of these (needs more testing)
• Squad members gain experience from combat (potentially hostiles killed?), shown by the number of chevrons next to their face picture, and improves stats (scavenging speed, chance to hit when shooting, and shooting range)
• Squads can enter vehicles and drive them around, and also shoot from them – but get a -30% chance to hit malus, even when staying still
• You can see the range and line of sight of the squad’s ranged attacks by hovering your mouse over their UI icon, to make sure they can hit what you want them to

Walls will create impassable areas, to limit access to your zone. Towers give secured points to deal damage to hostiles (depending on weapons assigned). Gates are secured points to deal damage, but also allow friendlies through.

• You can choose which weapons each tower/gate uses, which will then affect the range/damage/ammo usage. If you have no weapons of that type available, the tower/gate will not be able to attack – switch to bows & arrows
• Towers/gates are manned by workers; like most buildings, they only work when the workers are there, but the workers also don’t leave to sleep. These survivors do not seem to gain experience from combat done in the tower
• Towers/gates require stored ammo to use guns. Towers store 200 rounds (2 units of ammo) and gates store 300 rounds (3 units). Workers will leave to a warehouse to resupply, but only do this during the day – it helps to have a warehouse nearby regularly attacked areas of your perimeter.
• Walls will “snap” to the ends of other walls and the sides of gates, as well as the sides of buildings, but not towers
• Buildings are impassable (as they only have one entry point each) so can be used as part of your wall, reducing the amount of resources you need to secure an area
• Just like with squads, you can see the lines of sight and range of your towers/gates by hovering your mouse over the building

For simplicity, there are two kinds of buildings: secured, and empty. All adapted buildings become secured, whereas all others are empty.

• Squads can enter all buildings; hostiles can only enter empty buildings. As such, a secured building is better for defence than an empty one, as the hostiles will damage the building while your squad is protected and can fight back (as long as they have ranged weapons). Empty buildings are liable to be entered by infected or raiders to fight your squads in close quarter combat, which is extremely dangerous.
• Building height has an important effect. Weapon range is good, but squads also need “line of sight” on their enemy to target them. Setting up in taller buildings let swuads shoot over small buildings, or even over your own walls to allow them to safely backup your towers and gates.
• Every building has only one entry point. You can see where this is based on where your squad will path to, if told to enter the building. Keep this in mind if they are running from hostiles – it might just be safer for them to go to a further away building where the door is closer

Fight Smart: this goes without saying, and takes experience to get good at. Don’t fight infected in melee when you can hit them from range. Stay out of the line of sight of raiders with guns by hiding behind buildings, until you can engage them from within a building where you have cover. Infected run faster than your squads can on foot – make sure they stay far enough ahead to get to a safe spot.

Fortress: the idea of building up walls, towers, gates and barbed wire to protect your zone and direct hostiles to a specific area to fight back. Obviously resource intensive, but with careful planning and a good choice in area it’s possible to make strong defences, especially if you can get squads in high buildings to bring more firepower to bear in specific spots

Hit & Run: using at least 2 squads equipped with vehicles, have one stopped (and exiting the vehicle to remove the -30% aim malus) to fire at approaching infected while the other squad speeds ahead to get out and prepare to shoot. Micromanage intensive to stay ahead of melee, but this leapfrogging will let you do damage safely for as long as ammo holds out (though well prepared Operators will store ammo in the vehicles, to resupply the squads).

Kiting: if a group or swarm of infected is large enough to overwhlem your zone or a specific defensive point, you can use squads in vehicles to approach the swarm just close enough to draw off some the groups, so that your defences can handle a few at a time. One squad can also kite infected around a building manned by other ranged squads, that can fire on the infected without fear of them storming the building

Hunt & Clear: infected will hide during the day, usually in buildings but also occasionally in the ground. Though you can’t do much if they bury themselves, you can clear them out of buildings quite easily by sending squads in. Overwhelming firepower is good – multiple squads can be sent in at once. If a swarm is too big to fight in the night, you can clear them group by group during the day to stop them overwhelming your walls that night

Hopefully this information helps you build a successful, safe zone for humanity. With raw information you can optimise your play style, but remember to have fun and play around to see what works.

Last updated for game version 0.24.5.10 14 Beta