The Hunter R was a version of the Hunter α and was given an Umbrella development code MA-125 (the development code of the Hunter α was MA-121) and was intended to be the next step in Umbrella's flagship B.O.W. (Bio-Organic Weapon) intended for the mass market. The original Hunter was such a success that they wanted to iterate on it to keep their suppliers interested. As before, the Hunter R was created by combining human and reptile DNA at the embryonic stage and introducing the
t-Virus as a sort of emulsifier.
The Hunter R development was overseen by Dr.
William Birkin at his NEST facility, situated deep under Raccoon City. With the original Hunter, he saw quite a few limitations - such as it's large claws prevented it from being too dextrous and a little on the large size, making it fairly impractical indoors. So, he instructed his team to develop the creature to be more agile and more responsive.
The creatures themselves resembled the usual Hunter α with their scales, claws and green colouring; however they were slightly smaller and had distinctive spikes that ran along the length of their spine. They also have what seems like a permanent smile which is unsettling.
Development was suddenly halted when an incident at the NEST facility involving the Umbrella Security Service (U.S.S.) and Dr. Birkin - he was inadvertently shot and in order to save his own life and take revenge on the attackers, injected himself with the Golgotha virus (also known as simply G-Virus - which he also designed) which restored him to life but also mutated him into what would eventually be a monster named G. During the early stages of his mutation, he killed his attackers and then contaminated the water supply of Raccoon City with the
t-Virus which would eventually bring the city's existence to an end.
Some Hunter R's were presumably failed experiments or were killed at some point during testing as a few of them were found over at the Raccoon University which was fairly close to the NEST facility. Some were found strung up and others were placed on a table. One can only assume they were brought to the university in order to be studied there. It's not known if anything was gleaned from doing this, but many other versions of the Hunter series do exist so it is a possibility.
While a few fully activated and living Hunter R models were stored at NEST, they were kept under lock and key. However, due to the previous incident they were set free and mercilessly attacked all those in their path, deciding to hunt in packs to overwhelm their enemies. Their agility and smaller size definitely made a difference, although they were inherently weaker than the original model. They continued to prowl the facility until an Umbrella scientist escaped them, ran to a Low Temperature lab and brought down the temperature of the facility to a below freezing level.
This action put the facility in lockdown and disabled all elevators (and thus the only escape), but it did essentially freeze the Hunter R's so they could no longer move. They remained in stasis for some time until the temperature was brought back up to normal levels. Due to their resilience, the Hunter R's simply returned to normal and resumed their attack. It's likely that they have a built-in hibernation mode which kicks in when the temperature is sufficiently low enough.
These last remaining Hunter R's were later killed by a handful of survivors that were exploring NEST.
It's worth mentioning that the Hunter R does appear in the Nintendo 64 version of
Resident Evil 2, although their appearance is considered non-canon and they are more of an easter egg; especially as they are only corpses (and as part of the background art).
