I love mapping with the Source Engine. Here's a few scenes I've made within.
"dm_wastewater"(2019)
This was the first serious test of my level design skills. The level is split into four distinct zones of the basement, middle pool, upstairs and catwalks. There are a lot of fun environmental hazards, like poisonous water and a giant vending machine that players can punt around with the gravity gun. I learned when making this to keep scope realistic and playtest often, which I started a bit late towards polishing the map. Sight lines, especially in the upper areas, were a big consideration too, so I tried to make it so players often have a few ways to get out of the line of fire.