I've been a Half-Life fan for about a decade now although this has always perplexed me; does Deathmatch Classic even count as a Half-Life game? It has a guy wearing an H.E.V. mark 4 suit and some other Half-Life character models too I think, but then it's also heavily influenced by Quake 1 with the theme and the slipgates. Even Quake 1's rocket launcher is in there.
It’s Valve’s homage to quake
Something I'd like too see just for fun would be Gordon getting added to Quake Champions. Quake Champions also let's you choose from several skins for your character, for many pre-existing characters are from past games. For Gordon you could have the mark 4, helmet variant, DMC variant, the mark 5, helmet variant, scratched up variant, you could even give Gordon extra stubble like he does in Episode 2.