This Half Life photo contains
horse trail, horse wrangler, and wrangler.
There might also be
lippizan, lipizzan, lippizaner, saddle horse, riding horse, mount, street, city scene, and urban setting.
Youtuber user bloodrunsclear: "A long time request, based on the video game of the same name. I finally managed a perfect live action Gordon Freeman: Charlie Sheen from The Arrival."