Infection refers to how many mutants inhabit an area. There are three different types of infection that are listed in the game: Infection Rate, Infection Level, and Global Infection.
Global Infection is listed as a percentage. It is calculated from the Infection Level of each station sector, and thus serves as an estimate of how infected the colony as a whole is. It can basically tell the player how difficult the game is at a quick glance, because a higher number usually means stronger and more numerous enemies. The higher the number, the more tinted orange the number and the percentage bar will be. In addition, if the global infection is 25% or higher, then a number of mutants may attack Central Control directly in a mutant invasion.
Infection Level is listed as a percentage. It tells the player how infected a specific sector is. It works just like the global infection, except it is just one sector instead of all of the sectors in the game. The higher the number, the more difficult a sector will be to clear out; there will be stronger and more numerous enemies in a sector as the number increases. The higher the number, the more tinted orange the number and the percentage bar will be.
Infection Rate is how quickly the Infection Level is increasing in a sector. There are 4 subcategories that affect infection rate: Local Infection, Oxygen Level, Temperature, and Regional Spread. The first thing that is displayed is the speed of the infection with text telling how fast the infection rate is, and a number in parentheses; the higher that number in parentheses is, the faster the infection rate in a sector.
Local Infection is fixed at 20 for every sector except Central Control. This number almost never changes, and therefore makes it normally impossible to decrease a sector's infection rate to 0. Once the purification data is obtained, a sector can be purified by installing the purifying filters that can be produced, but all local infections will triple to 60 until the sector's purification is complete.
Oxygen Level refers to how high the oxygen level is in an area: the lower the number, the lower the infection rate. To improve the oxygen level in an area, install an oxygen filter in the area. The higher tier that the oxygen filter is, the more it will decrease the Oxygen Level number, which will further decrease the infection rate.
Oxygen Level varies from 0 to 50, based on the sector and its installed filter. With a purification filter, the oxygen level is 0. With an oxygen filter MK III, it is 9. With MK II, 18. With a basic oxygen filter, 30. Without a functioning filter powered, each sector will stabilize at different oxygen levels, which affects both how quickly West's oxygen canister depletes and the sector's oxygen level (with respect to infection rate; see table). Central Control stabilizes at 60% oxygen, core sectors at 50% oxygen and 40 oxygen level, inner sectors at 35% and 43 oxygen level, outer sectors at 15% and 47 oxygen level, and all other sectors at 0% and 50 oxygen level.
Temperature refers to how high the temperature is in an area: the lower the number, the lower the infection rate. To improve the temperature in an area, install a thermal regulator in the area. The higher tier that the thermal regulator is, the more it will decrease the Temperature number, which will decrease the infection Rate more.
Temperature varies from 0 to 50, based on the sector and its installed regulator. With a purification regulator, the temperature is 0. With a thermal regulator MK III, it is 9. With MK II, 18. With a basic thermal regulator, 26. Without a functioning regulator powered, each sector will stabilize at different temperatures, which affects both how quickly West's thermal canister depletes and the sector's temperature (with respect to infection rate; see table). Central Control stabilizes at -4ºC, core sectors at -10ºC and 40 infection temperature, inner sectors at -19ºC and 43 infection temperature, outer sectors at -31ºC and 47 infection temperature, and all other sectors at -40ºC and 50 infection temperature. Naturally, the infection temperature of all sectors will triple when the purification data is obtained.
Regional Spread is caused by a nearby sector carrying an extremely high infection. A sector typically begins spreading out slowly at about 80% infection, and gradually increases in its influence as the infection increases. All sectors within another sector's regional spread gain 5 Regional Spread, and this can accumulate if more than one nearby sector is sufficiently infected. Like all infections, Central Control is unaffected by regional spread.
- The easiest way to decrease the infection level in an area is to kill all the mutants you see and to place oxygen filters and thermal regulators in an area. However, this is both time-consuming and resource intensive.
- Maintaining a low infection level in the core sectors is both easy and useful for deterring mutant invasions from those particular sectors.
- While a sector has an oxygen filter or thermal regulator installed and powered, the infection rate will decrease, but the infection level will still increase steadily while it's not purified, so keep an eye on it.