MP5 (Evolution)

The MP5 is a weapon in Half-Life, also sometimes called the "9mm Assault Rifle" or the "Submachine Gun". Throughout the development of Half-Life, it got its own fair share of changes. Curiously being one of the only weapons to remain almost identical to it's earliest stages throughout development, the changes it did end up receiving were quite substantial.

Version 0: Concept Art

Before the MP5 was decided upon, Valve was considering using other weapons to use as their fully automatic gun. Firstly was the H&K G11, which did end up being modelled at some point, being used by the earliest versions of the HECU before their redesign. During their redesign, the HECU was given the M16 rifle with a M203 grenade launcher attachment. Ultimately the M16 rifle was chose and can be seen in the earliest available HECU meshes. Eventually the M16 concept was discarded in favor of the MP5SD.

Version 1: Pre-Alpha

The earliest appearance of the MP5 known. This version sports no hands, a temporary feature short-lived which retained for quite some time in the Alpha Crowbar. It also has a more brighter and unique textureset compared to later revisions of the MP5. The weapon's first person origin point is higher up the players view height.

Version 2: Alpha

This version can be seen in the leaked Alpha 0.52 build, now being held by two bare arms. This version had a much more elaborate texture set - having a more detailed buttstock and reciever, as well as a green M203 grenade launcher - and would be used as a basis for later versions to come. The origin was now adjusted to be more on the side compared to the previous iteration.

Version 3: Late Alpha

Moving onto the later Alpha, in this version an early appearance of the HEV suit can be seen, although only with red sleeves and bare hands. Interestingly the mesh for the model was squished down on the Y axis, presumably to take up less screen space. This model's source files can be found in the Half-Life SDK as it was also used for creating the weapon's animations. This version of the weapon had a somewhat short lifespan as it was later replaced with the more long standing next version. Around this time, the model also received it's first worldmodel, looking very blocky and detailed.

Version 4: Beta

This version finally acquired the gloved HEV hands we know and love, except the glove chrome was a simple gradient as opposed to the detailed chrome texture used for the gloves at the time. Despite this, the hand mesh is virtually identical to the previous versions, with no knuckle armour, as well as having the HEV sleeves covering up the missing faces. At some point, this version of the model was given a centred origin and had a much more elaborate reload animation where Gordon raised the gun and dumped the magazine before reloading.

Version 5: Retail

This is the final version of the model, being seen in Half-Life's last stage of development as well as the game's release in 1998. The arms finally have detailed chrome and orange arms, bringing them in line with the other viewmodels. Additionally, the MP5 itself got a slight remodel, with a more realistic backsight and chrome present throughout the model. The M203 grenade launcher was also made grey to blend with the rest of the gun. Gordon no longer raises the gun as prominently whilst reloading. Curiously, the worldmodel of this version of the weapon resembles a MP5A3 instead of an MP5SD.

Version 5.5: Gearbox

At some point in 1999, Gearbox Software created a whole new rig for the MP5 based on the "Bip01" system instead of the "BoneXX" system used by Valve's model. The mesh of the MP5 was the same, however the animations were completely redone. This model was seen in Opposing Force and Blue Shift.

(todo: article needs more work)