I do enjoy mods that are still tinkering with games of days gone by, and this is no exception - as one mod author has now ported the higher quality PlayStation 2 assets from the original Half Life to the PC version, creating the definitive version of the original.
If you're not a fan of the various, and often unfinished, attempts to re-create the game such as Black Mesa, which recently suffered another delay, and prefer to play the game as originally intended, this mod provides the best combination of high quality assets, which look great at the higher resolution the PC can afford over the PS2.
The assets include higher polygon models, with better quality textures, and also includes the new maps that were featured in the PS2 version. As an added bonus, the Spanish and English audio from the PS2 version is also ported over to the PC here.
The mod only works with the Steam version of the game, and not an original retail boxed copy, but if you're interested in picking this up, the download link is here.