Suddenly remembered a question I had many years ago for some reason, thought I'd ask again here to see if an answer had been found in the 6 or so years since then.
As you all already know, back in 1999 and maybe 2000, some enemies were already created during the Hyperborea-start era before they retroactively became a part of the Combine once the idea of the Combine as the main enemy faction was conceived. The Sackticks used by the warrior aliens that preceded the Combine was confirmed to be one such enemy, and the Stalkers may have been a pre-Combine enemy too since we know it is one of the earliest enemies made for HL2 as well as how prevalent they are in the Borealis/Kraken Base/Vertigo maps, all of which are locations in the Hyper-start era before they were moved to be near the end of the game after the Combine was introduced.
But what about the Combine Soldiers then? Combine Soldiers must have been made very early on too as the successor to the award-winning HGrunts, but was that really the case? They can't have been an enemy carried over from the pre-Combine era since their entity name is npc_combine_s, which means they must have been programmed after the Combine's conception. But if that's the case, then what kind of human soldier enemies were used in the maps made before the Combine existed?
Were the missing old storyline hyper/deep/spire/urb maps completely devoid of human soldier enemies until they came up with the Combine and its npc_combine_s, or did those maps feature a different kind of human soldier enemy NPC entity that has since been obsoleted with all traces of their existence removed as soon as npc_combine_s was programmed into the game? If the latter is true, were the earliest Combine Soldiers designs recycled from these hypothetical npc_hgrunt2, or did these hypothetical npc_hgrunt2 feature a different design that we have yet to see?
Problem is, no such entity has been found yet in the WC Mappack. The oldest map in the WC Mappack, c1a3a_port (December 2000), already featured npc_combine_s in the place of monster_hgrunt. Combine is also mentioned by name in the Soldier Skyscraper dialogue (17sky_sol1.wav, November 1 2000) and the early Alyx Citadel dialogue (citadel3.wav, October 28 2000). Either Metrocops or the trenchcoat Combine Guards already exist as of July 2000 since that's when Get Your Free TVs with the HL1 HUD was shown off at SIGGRAPH 2000. This means that the idea of the Combine and the circular C17>Wasteland>Arctic>C17 storyline already existed by summer 2000, thus putting the timeframe for the hypothetical existence of pre-Combine human soldier enemies in the Hyper>Deep>Spire>Urb era in 1999 and perhaps early 2000. For comparison, the Odell voiceline that mentioned the Sackticks (odelltest.wav) is dated November 11 1999, which could mean the Combine weren't conceived yet and the game still revolved around the 3 alien races on Earth at that point or the Sackticks were already a part of the Combine by then. It also begs the question of whether the Arctic Spire maps were conceived as the Combine's Weather Control station from the start or if it was just a facility used by whatever the enemy soldier faction was at the time until they slowly morphed into the Combine over time.
tl;dr What I want to know is whether
1. A direct port of HL1 HGrunt was used as placeholder human soldier enemies in 1999-era HL2 maps until npc_combine_s was made
2. A different successor to monster_hgrunt with a different entity name was used as human soldier enemies in 1999-era HL2 maps until npc_combine_s was made (and if this is true, was the oldest Combine Soldier model recycled from this hypothetical enemy?)
3. No human soldier enemies were used in 1999-era HL2 maps until npc_combine_s was made
I don't suppose we'll ever get an answer to this question without the miraculous leak of 1999-era HL2 screenshots/footage/assets/builds before our eventual demise, so feel free to post your most educated guesses on the topic here in the meantime.