Even simple Half-Life 1 mods built on textures and models from Half-Life 2 look much closer to 2 than one would expect. For example this mod, but not only:
You won't confuse it with modern Half-Life 2, but the original HL2 engine had far worse graphics than the latest version. Makes you realize how much of the difference between HL2 and HL1 is due to different textures and level design.
https://moddb.com/mods/half-life-dark-future
You won't confuse it with modern Half-Life 2, but the original HL2 engine had far worse graphics than the latest version. Makes you realize how much of the difference between HL2 and HL1 is due to different textures and level design.