It was a much simpler time back then.
Photographic perspective correction and simple UV project from view was the dominate go to.
Basically, everything was a real-life source texture stamp. 
For this style, don't overthink it fren.

? Original Texture Source Photography from Half-Life 1 - YouTube

Hey there! Some of you already know me as a Sound Designer who usually post videos about my projects, or tutorials. But today is a bit different and a little more directly related to this community. I am working on this little old school text based video game, but I am actually using web dev tools …