Boiler are a strain of Chimera that exclusively appears in Resistance: Retribution and are first referenced in an Intel Document in Resistance 2. They are exclusively mutated from human female subjects.
The Boiler was created for the purpose of invading the warmer climate of Africa. This strain can tolerate warmer temperatures better than most other Chimeran creatures can. There are two known notable Conversion Centers in Europe that converted these strains: Bonn, Germany and the Chrysalis Lair in Paris, France. Within these conversion centers, many comatose women flow through the pipes, and it is stated that the women are injected and gassed, mostly whilst suffocating and submerged in water. Also it appears that the Boilers in these unique Centers replaced the workforce of the Menials.
Boilers have a rather human appearance with the exception of an extremely overgrown head in a way that resembles to Daedalus. They also seem to have had their hands and feet mutated to resemble tentacles. Furthermore, Boilers greatly resemble Hags, though with a smaller head and a comparatively less feminine face.
The Boilers are, in combat at least, mostly suicidal and never use any apparent form of strategy or tactic (given their volatility, this was probably never needed anyway). The Boilers were most likely the predecessors to, or simply the female version, of the Leech, seen two years later in Resistance 2.
Boilers attack by self-destructing while releasing a powerful kinetic wave from their heads. They have hard, leather-like skin, which is durable in gameplay, and the recommended way to kill them is to shoot them in the head with weapons with high accuracy such as the Storm Rifle and Fareye FR-1. Luckily, the Boilers' heads appear to be very fragile, and will be destroyed easily. The player can try to shoot them in the body, but they can withstand much more damage than other basic Chimera, and will take longer to kill.
- Its name might come from their psychic powers, but as the game hints, may have something to do about an incubation that is quite short and similar to actual boiling.
- The Royal Marine that appears in The Guns of Rotterdam explains what Boilers are to Grayson by mentioning "Plumbing's gone, just like a menial except under it's knickers". It is worth noting for the fact that after conversion Chimeras such as Menials and Hybrids and so forth have no genitalia (or any real noticeable gender) and despite hybrid strains of Chimera being androgynous in appearance, Boilers are noticeably female.
- It's interesting to note that boilers are not deployed on offensive engagements, and therefore have no armoured/assault variant. This, coupled with the fact they are only found in or around the facilities they are created in, one can assume they are deemed for defensive purposes as a quick way to neutralize unprepared attackers or as a suicidal last line of defense.
- Due to the fact they do not appear in Resistance 2; set two years later after Retribution, they may have been deemed ineffective and removed from Chimeran units, or as previously stated, Boilers are defensive units or exclusive to the European front. Or simply because the second conversion method has been discontinued and Boilers are no longer produced.