I had a fanfiction that I still consider canon in my head where Magnusson, Otis, and Gus escape Black Mesa as a group.
People who want lgbt rep in Half-Life wasting their time with Gordon/Barney and ignoring the superior Griggs/Sheckley, Gina/Colette, and literally every Vortigaunt.
I'm fairly sure the lore on Portal Storms indicate that it causes random teleportation events, and that we saw them spreading Xen wildlife throughout the first game before HL2 named them. Gordon and Alyx were probably lucky not to have been teleported to god knows where in Episode 2. This is probably why Xen is such a difficult place to live; it's probably wracked with portal storms shoofing you to another island when you least expect it. On the other hands, that's probably how life propagates across the floating islands without flight.
I had a dream that Half-Life Alyx got a DLC that introduced yet another headcrab species called "the Wig" that resemble a giant dab of whipped cream with headcrab legs. The zombie it created was able to shoot a giant tentacle that looked like elephant's toothpaste out of its maw.
(Edited)
I feel any post-Combine human government, during the immense struggle to get the Xen wildlife under control, is going to decide to leave the barnacles alone with just some warning signs because they're such a convenient anti-headcrab measure.