Proto:Half-Life 2 (Windows)/September 26th 2003 Build/Used

Clues point to Half-Life: Alyx being more than than just a prequel

Alyx's Gun, Half-Life Wiki

Half Life 2 Jacket

Half-Life 2 Alyx Vance Jacket

Rebel Alyx [Half-Life 2] [Mods]

Half-Life: Alyx - Who is Alyx Vance?

Falemirous Half-Life 2 Alyx Mod: Version 2

Here's Half-Life 2 running in VR, using Half-Life: Alyx's engine

Half-Life: Alyx] Vanilla Combine Soldier found within the Half-Life: Alyx file directory ported to Half-Life 2. Available for download and installation for Half-Life 2. (Link in the Comments) : r/HalfLife

Half-Life