Aggro range explanation

[TV.BrettKelly89]

Hello everyone I have been playing this game for a few weeks now (started on Brutal~Brutal and im still on the first map!). One of the issues im having is that the aggro range of zombies seems to be inconsistent throught the map. I normally expand with a row of units, typically soldiers, and clear then move up, rinse, repeat. However i regularly run into an issue where they start pulling from 4x the range they were just 1 unit away.

My question is can anyone explain how aggro works? Is there different aggro ranges the further you get from the CC? Is there any way to know youre pushing to far into the next increased aggro range other than pulling 200-500 zombies?

[HijackDallas]

The SMG of a Soldier is loud. Noises attracted many Zombs.

Thats why I use many times Ranger, the quietest Unit.

Or Soildier with Ballitsa or Sniper support, to dry VoD´s out or directed the Zomb to a certain area to kill them.

[Andrewbh2003]

the range at witch zombies hear noise is based off of several factors including noise there direct "agroo" is very small aka they have very bad los so they wont see you until there 2 feet in front of your units what works is the noise everything from buildings to units to zombies themselves generate noise obviously a rangers bow makes less noise than a soldiers smg or a sniper bullet but also each individual zombie type has different noise detections thats why sometimes your clearing a horde of weaklings then suddenly out of the grey fog of war a few runners come by to say braainzzzzz

also yes the rule is you always spawn in the very center of the map the closer to the edges of the map the stronger the zombies aka the bigger the "agro range" is as in the noise generated also be wary when building walls just the act of building stuff can generate noise as well just think what would cause noise in real life ^^ check the they are billions noise wiki section for more info

[Liro Raériyo]

from what i can tell, "noise" is generated with actions happening on the map, while i do not believe construction has much impact on this, continuous attacks from anything but a pair of rangers most certainly generates "noise" in an area faster then it disipates, and i mean ANYTHING, zombie attacks generate noise as well which will self feed until literallys swarms are on your CC

[Andrewbh2003]

Originally posted by Liro Raériyo:

from what i can tell, "noise" is generated with actions happening on the map, while i do not believe construction has much impact on this, continuous attacks from anything but a pair of rangers most certainly generates "noise" in an area faster then it disipates, and i mean ANYTHING, zombie attacks generate noise as well which will self feed until literallys swarms are on your CC

construction of certain things does cause noise and rangers do still generate noise just in very small ammounts but yeah if 15+rangers shoot at the same time in the same area it will generate moderate noise enough to atract a small group and zombies dying also generates some noise

[HeadStrikeR !]

Noise is accumilated on the tiles, pressing F4 for flatmode shows you these tiles. If a tile gets too much activity zombies become more active. Soldiers are loud and have to be handled more carefully, especially on map4.

You can counteract the noise/activity accumilation by switching tiles often and don't stick units together. If you keep activity low, zombies will never go crazy.

Attacked wall pieces also skyrocket your activity, since you will most likely try to fight back and you gain noise from zombies pounding on the walls and you units desperately trying to kill them off.

Another thing which generates a lot of noise is when zombies infect a building.

[Andrewbh2003]

Originally posted by HeadStrikeR !:

Noise is accumilated on the tiles, pressing F4 for flatmode shows you these tiles. If a tile gets too much activity zombies become more active. Soldiers are loud and have to be handled more carefully, especially on map4.

You can counteract the noise/activity accumilation by switching tiles often and don't stick units together. If you keep activity low, zombies will never go crazy.

Attacked wall pieces also skyrocket your activity, since you will most likely try to fight back and you gain noise from zombies pounding on the walls and you units desperately trying to kill them off.

Another thing which generates a lot of noise is when zombies infect a building.

[TV.BrettKelly89]

The tile stacking noise thing makes sense @HeadStriker. I will pull harpies with any unit at some point in the game, generally at the end of the second expansion. This is why i was wondering what was up but that seems to make the most sense. So basically you need to move constantly.

As for everyone thank you for the advise.

[UFO]

Noise/aggro is nice to exploit, like when "draining" a damned village or funneling zombies into a kill zone. Snipers work pretty well, but a single Thanatos rocket can draw in zombies like flies. This is also one reason why you should avoid picking a mayor that gives you a free Thanatos - not too fun having half the map bearing down on you on day 14 because Mr. Narcissism-with-legs decided to blow up a lone zombie milling about outside of the wall...

[Qiox]

Here is how the 'noise' system works as explained in the top comment of this reddit thread:

https://www.reddit.com/r/TheyAreBillions/comments/7n0p97/can_the_noise_system_be_explained_better/

[TV.BrettKelly89]

good article

[TV.BrettKelly89]

So can anyone explain why aggro ranges seem to multiply the further you get from the command center? I know that 8 archers dont pull as much aggro as 8 soldiers but yet still pull harpies from the same distance?

[Glowth]

Originally posted by Killsquad:

So can anyone explain why aggro ranges seem to multiply the further you get from the command center? I know that 8 archers dont pull as much aggro as 8 soldiers but yet still pull harpies from the same distance?

You misunderstood something. Harpies multiply tile activity by 8 so they detect noise from much further than any other zombie. With enough noise they can be attracted from even something like 72 tiles away, even more on map 4 since activity deteciton is boosted on that map.

Near command center there is only usually decrepits olds and yongs basically trash zombies that are very deaf, further out there are runners and specials that multiply activity and detect from further away.

[TV.BrettKelly89]

Originally posted by Glowth:

Originally posted by Killsquad:

So can anyone explain why aggro ranges seem to multiply the further you get from the command center? I know that 8 archers dont pull as much aggro as 8 soldiers but yet still pull harpies from the same distance?

You misunderstood something. Harpies multiply tile activity by 8 so they detect noise from much further than any other zombie. With enough noise they can be attracted from even something like 72 tiles away, even more on map 4 since activity deteciton is boosted on that map.

Near command center there is only usually decrepits olds and yongs basically trash zombies that are very deaf, further out there are runners and specials that multiply activity and detect from further away.

Rangers generate a base activity of 1 per shot
Soldiers generate a base activity of 3 per shot

You misunderstood something. Here i posted it for you.

Harpies should that are pulled 72 tiles by archers should in theory be pulled from 286 tiles by soliders? Thats your statement above? Really? So basically thanatos (aggro ranged on rockets listed below) can pull harpies from 72x500 = 3600 tiles away? Man math is hard for you guys

Thanatos generate a base activity of 500(!) per rocket attack

[Glowth]

Noise
http://they-are-billions.wikia.com/wiki/Noise

Zombies are attracted by "noise", which is simulated in the game as a numerical value called 'activity'. Within the community, the terms noise and activity are generally used interchangeably. Activity is added to each tile by different events that one would understand logically produce sound. The activity level in an area can be estimated by the player but is not visible directly. The higher the activity in an tile, the further away the game engine checks for infected to 'hear' the activity and come to investigate. Whether an individual infected hears the noise is determined randomly, so essentially for a given level of noise a certain percentage of infected within a given range will come to investigate.

Many higher level infected are more alert and more responsive to noise. An alertness factor modifies how loud a noise is treated by each infected, and consequently from that how far away the infected may be and still hear the noise. While slow zombies multiply base activity by 2, fast zombies and fatties multiply it by 3, venom infected multiply it by 4, and harpies multiply activity by 8.

With very heavy noise, a Harpy can be attracted from up to 72 tiles away (maps 1-3; and even further away on map 4), while other lower level zombies would need to be much closer to have any reaction. This is also why, when clearing out an area, it is not uncommon for many of the walker tier zombies to not react at all, while a few "runner" zombies come bounding in from further away. In general, zombies can hear much better than they can see -- it is much more likely that a zombie comes running over because they heard a bunch of gunfire than it is because they saw one of your units or buildings themselves.

Noise is produced by a variety of activities. Some examples of noise production:

Attacking with an ranger produces little noise, or 1 activity per attack.
Attacking with a soldier produces moderate noise, or 3 activity per attack.
A Ballista firing produces a moderate noise - 5 activity per shot. However, because the ballista can do a relatively large amount of damage per shot, the total noise generated by a ballista to kill a given number of zombies is among the lowest in the game.
Attacking with a sniper produces higher noise, or 10 activity per attack.
Attacking with a Titan produces very high noise, or 20 activity per attack.
Attacking with Thanatos produces extremely high noise, or 500 activity per attack.
Like units, the attacks of infected themselves also generate noise with each attack. The more dangerous the infected, the more noise its attack generates. Infected attacking a structure, such as a wall, can therefore set off very dangerous noise cascades, where the noise of the attack on the wall and even the attempts of the player to kill the offending infected, themselves produce even more noise that attracts more and more infected at an exponentially increasing rate.
Zombies infecting a building produces 50 noise per worker or population in the building. Thus the amount of noise generated can be moderate for infecting a Tesla tower, or extremely high for infecting a farm or stone house.
Infected breaking a wall or building produces a large amount of noise.
Note that the attack speed of a unit affects its effective noise. Thus, a veteran soldier will tend to generate more noise than a newly created sniper. Also note that since the distance over which the game checks for zombies to be alerted by noise depends on the noise level, longer ranged weapons tend to pull relatively fewer adds than shorter ranged weapons by the simple virtue of being further away from any infected that are currently not aggressive.

If a zombie is attracted to an area because of noise, it will walk there and "investigate". If the source of the noise is no longer present (for example, if you were clearing with 10 snipers then moved them away) it will stay in that area and will not be able to chase after the "true" source of the noise, because as far as the zombie is concerned, the source of the noise was that exact spot on the ground.

When noise is produced, the game adds activity to a tile, and a smaller amount of activity to adjacent tiles. The exact amount of activity added to a tile other than one that the noise occurs in is not known. However, the fact that activity is added to both the tile and adjacent tiles is the reason that groups of units working in a small space are much 'louder' than units that are spread over a sufficiently wide area. The noise level that each of these affected tiles has will decay to 0 over a few seconds. Existing activity decays to half of its current value every second. Thus, an ranger firing continuously does not accumulate much noise over time. However a veteran ranger with a higher firing rate can accumulate much more noise, which is observable on map four. Different sources of noise stack up with each other, if the activity adds up faster than it can decay. While 5 Rangers are very quiet, 50 Rangers within the same small area can be quite loud.

Note that kiting a noise producing unit spreads the noise over more tiles, resulting in less activity than if the unit stood in one place and continuously fired.

Noise level can also be used to the player's benefit by using loud units to attract as many zombies in an area as possible. For example, with a band of 20+ snipers shooting off their rifles, or by blasting an area with a Thanatos.

Zombies are much more sensitive to noise on Map 4 but much less sensitive to noise on Map 3. On map four the usual distance that he game checks to see if a zombie hears noise is multiplied by 1.5. For example, if sound might normally only be heard by zombies within 6 tiles, on map 4 it can be heard by infected up to 9 tiles away. This causes even very small sounds, such as a ranger firing, which would normally not be heard from further away than the infected's view range to become significant. For loud sounds, generally more than twice as many infected will arrive to investigate as would normally be expected, which can very quickly create cascading problems as dealing with the adds causes even more noise to be created leading to uncontrollable difficulties.

[Glowth]

Originally posted by Killsquad:

Originally posted by Glowth:

You misunderstood something. Harpies multiply tile activity by 8 so they detect noise from much further than any other zombie. With enough noise they can be attracted from even something like 72 tiles away, even more on map 4 since activity deteciton is boosted on that map.

Near command center there is only usually decrepits olds and yongs basically trash zombies that are very deaf, further out there are runners and specials that multiply activity and detect from further away.

Rangers generate a base activity of 1 per shot
Soldiers generate a base activity of 3 per shot

You misunderstood something. Here i posted it for you.

Harpies should that are pulled 72 tiles by archers should in theory be pulled from 286 tiles by soliders? Thats your statement above? Really? So basically thanatos (aggro ranged on rockets listed below) can pull harpies from 72x500 = 3600 tiles away? Man math is hard for you guys

Thanatos generate a base activity of 500(!) per rocket attack

You have totally misunderstood the point. I never specified a unit type or amount. A group of ranges big enough to attract a harpy from 70+ tiles makes less noise than a group of soldiers the same size.

I did the math and I am not sure whats with the noise tbh since according to my calculations you would instantly bring all the witches to a single thanatos firing a few shots, no idea.