HECU Soldiers (Evolution)

The Human Grunts - often referred to as the Hazardous Environment Combat Unit and it's acronym HECU - are ruthless troopers found throughout Half-Life starting with the chapter We've Got Hostiles!; Tasked with purging Black Mesa of any living creatures, they are merely one of many obstacles the player has to face. Before they settled on their final design, they went through a good few revisions prior to their final design, though they arguably remained the most consistent throughout development.

WARNING: The following article is going through a comprehensive rewrite. Currently it is incomplete and needs more work.

Version 0: The Green Soldier

Very little is known about this model, as due to it's appearance in only one screenshot it is one of the most obscure and unknown Half-Life models. This model was only ever seen in the first Half-Life screenshot, halfldoctorback.bmp. This grunt had a green jumpsuit, black boots, black body armor and while the head isn't too visible, it's likely he wore a black gasmask. The weapon he carries isn't too visible, as it's also coloured black like his body armor. However, a H&K G11 was discovered in the Half-Life SDK, matching concept art for the following version. The gun has no textures, but it's modelled muzzleflash does. As Half-Life used sprite-based muzzleflashes even as far back as 1997, this was likely a VERY early leftover.

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  The alleged first Human Grunt.

Version 1: The Human Sergeant

This is the earliest model we have. This version of the Grunt has lower quality textures compared to the final model. Additionally, his shoulders are wider and sharper, he has a unique sleeve texture with a US Marine Corps tattoo, suggesting this is who the player would be fighting against. Further more, their vest is merely a harness, with their pouches being more closer to lime than army green. Compared to later revisions, this one has gloves. This model notably features in an early render with a Scientist and Panthereye. Of note is the high quality flashlight and gun models; The gun specifically is a Walther MPL without the back stock.

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  A render of the earliest Human Grunt model, then titled the Human Sergeant.

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  The infamous render.

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  The Walther MPL.

Version 2: Gloveless Grunt/Camo Variants

This version is seen in very early screenshots alongside Ivan the Space Biker, the direct predecessor to Gordon Freeman. This grunt finally has a vets, with a new amber-coloured radio, and his bright green pouches are now a duller military green colour. The texture resolution is overall much higher than that of the previous version or any subsequent versions. He also carries an AR-15 patterned rifle with an M203 underbarrel grenade launcher. However, the most interesting thing about this grunt is its' two variants, Olive.mdl and Desert.mdl, which survived into the 0.52 Alpha, albeit merely as vestigial leftovers. They are not used in game, merely just existing in the files. It is these variants that were used as placeholder multiplayer models in staged screenshots showing a group of Ivans and Grunts duking it out. The mesh for this version can be found, labelled as reference(old).smd in the Half-Life SDK's model sources.

Version 3: 0.52 Alpha Grunt

The Grunt model from the leaked 0.52 Alpha Half-Life build. This version is closer to the final version, with the final glove textures finally making their appearance. Otherwise this version is pretty close to the previous revision, with slightly lower resolution textures. The grunt still carries his olive-tinted AR-15.

Version 4: reference.smd Grunt

Seen in the Half-Life SDK, this version of the Grunt seems to be largely identical the 0.52 model. Along with having numerous UV errors, it is the last to have thin biceps and shoulder guards. This version of the Grunt changed his arsenal too, swapping the AR-15 for an MP5SD, identified by the intergrated suppressor barrel.

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  reference.smd Grunt

Version 4.5: Early Robo-Grunt

To skirt censorship laws in Germany, which were strict around fatal violence against humans, Valve opted to replace most human entities with robotic doppelgangers, and the Human Grunt was no exception.

Version 5: Half-Life: Day One Grunt

As seen in Half-Life: Day One, this Grunt is near completion, as he carries an MP5A3 and has an alternate head with a beret and scowl. Otherwise, this is almost identical to the retail model.

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  Day One Gasmask Grunt

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  Day One Beret Grunt

Version 6: Retail Grunt

The final version of the Grunt as seen in the retail build of Half-Life.