I previously posted a video and some pics on Half-Life 2 co-op using the mod Synergy. We continued through Episode 1 and Episode 2. This mod is amazing as you can experience the episodes with a friend or a few friends and save Alyx again and again. Not only that, but Alyx will ride along, fight with us and insurgents as well! There are even some unique scenarios that would never happen playing single-player.... like you can drive a buggy in Episode 2 and your friend can ride along while using the gravity gun and a sticky bomb.
There were a few bugs in Synergy but were not the fault of Linux. Like your character can get stuck between two NCP's who are acting out a scene. Sometimes the hotrod was the only car to drive and the other players had to travel on foot. Sometimes we wouldn't have the gravity gun at all and other times the automated elevators didn't work properly. There were times Alyx wasn't with us and there was a door she needed to open. We would have to just restart the level. There is a great auto-save/checkpoint feature, but sometimes you have to do all the puzzles or wave-based scenario over and over again.
Each episode ran beautifully in Linux and brought back all the nostalgia from playing it years ago. What a beautiful engine!
Mint 20.1 64-bit
GeForce GTX 1060