Warhammer 40000: There Is Only War mod for Half-Life 2

     The Death Korps are an Imperial Guard regiment from the Imperial world Krieg and are notoriously grim and fatalistic warriors.

     Appearance-wise, the Death Korps are similar to the Armageddon Steel Legion,
but have darker colors, and their masks usually have a skull motif. Of
all the regiments of the Guard, they are the most grim and fatalistic,
both in appearance and in spirit due to the 500 years of atomic purging
the inhabitants of their home world inflicted on themselves. Uniform
cut and design is almost consistent throughout the entire Death Korps
but colours can vary from regiment to regiment and the officer ranks
tend to have slightly more ornate uniforms than the rank and file.
Spiked helmets are famously worn by the Death Korps of Krieg however
this is rarely the case, but many troops maintain the tradition either
with improvised spikes or, less commonly, older issues of the spiked
helmet that have survived and been passed down through families.

     Death Korps units prefer to use Meltaguns and Heavy Bolters,
but also have access to Mortars, Heavy Stubbers, Lascannons,
Autocannons and Flamers. As with most Imperial Guard their standard
issue individual weapon is the Lasgun and many carry a Laspistol. The
multi purpose knife carried by all members of the Death Korps is a
bayonet but also a field tool. The citizens of Krieg are gloomy but
hard working, and this is reflected in the weapons and equipment used
by the Death Korps which is very utilitarian compared to many Imperial
Guard regiments, but ultimately, fit for purpose.

     Orks are a warlike, crude and highly aggressive green-skinned
alien race. Orks are the dominant subspecies of the Orkoids, which
includes the smaller Gretchin and Snotlings.
Although their society is entirely primitive and brutal, the Orkoid
race is also the most successful species in the whole galaxy, spread
throughout the galaxy and outnumbering possibly every other race.
However, due to this aggressive and warlike nature, the massive race is
split into hundreds of tiny empires, warring as much between themselves
as against other races. In the purely theoretical event all the Orks
were to unite, they would undoubtedly crush all opposition.

     Ork "teknologee" appears ramshackle and slapped-together, but is as potent as any weaponry used by the Imperium.
Ork technology is characterised by a constant stream of poorly
thought-out experimentation and constantly trying to outdo the
competition to build the biggest gun, the largest Gargant,
or the fastest Warbuggy. Therefore Ork technology is not uniform,
lending Ork Warbands a cobbled together and random appearance. Ork
Mekboyz are specialists in the field of producing powerful Force Fields
that can protect against damage, and at battlefield improvisation of
repairs. They can salvage almost any burnt-out wreck, and many Ork
vehicles have been reported destroyed dozens of times, only to be
cobbled back together, given a fresh lick of paint (if even that), and
sent back into the fray. The tough, resilient nature of Orks means they
accept crude bionics enhancements, transplants, and other medical
shenanigans being performed on them with ease.

all information from the lexicanum