Could Op4 be retconned to fit cannon?

A fourth, seperate kind of headcrab?

Maybe it’s the glowing green radioactive crap it seems to be filled with?

i just assumed that was part of the crabification process.

Yeah, I always believed they were slowly developing into a Gonarch.

Yeah, eventually the entire body sorta melts into a giant ball sack and hops around after you like a guy in a sackrace.

There are no Gonomes in HL2, and there isn’t any neon-green waste in HL2. Gonomes are covered in green bubbles and throws toxic green globs at you.

A scientist even says that it’s the next stage in their “Mutation” and not “Life-cycle”

I’m still certain he was referring to the crab’s transformation of the host’s body, i don’t think they meant mutation in the 'toxic avenger" sense. The neon green stuff is irrelevant, it was on the normal zombies in the HD pack. Valve just didn’t wanna run with that gonome concept in the sequel, i guess.
Except for whatever the hell this was:
https://images2.wikia.nocookie.net/half-life/en/images/3/34/Zombie_Assassin_model.jpg

Looks like a fast zombie with flesh still on.

There was going to be an enemy called the Combine Prowler and that was to be the zombie version of it, but it “evolved” into the Combine Assassin and the fast zombie.

It was called the Alien Assassin. I hate when people call it the “Prowler”. It, the Combine Assassin & the Fast Zombie were 3 completely separate things, it was the AI that more or less carried over to the fast-zombie.

The HD pack was created by Gearbox too. The scientist zombie’s have half as much green goo in/on them as the Gonome, the barneys only have part of their arm, and the soldiers only have a tiny bit on the elbow. It’s the different toxic-waste exposure levels. None of the Green goo is in HL2, so it justifies why you don’t see gonomes in HL2.

How exactly would a headcrab turn into a zombie, then back again into a giant crab?

Actually they throw bloody red spiked teeth at you, which they pull from the teeth in their chest.

Just because i liked Opposing Force, you don’t need that much of reason to believe it is canon.

Yep, the Chicken Cannon could do it.
https://www.youtube.com/watch?v=kdeg9izJE3I

We may need to blend it first.

I’m excited! Fire it into the sun!

https://img407.imageshack.us/i/monstergonomeqe7.jpg/

Radiation you say? Well, I suppose that could be reason…

I really wana know how long the process takes to become a headcrab zombie. That would help so much.

Ok, I missed one detail. The rest is still valid.

I don’t see why it couldn’t be canon. Race X? Gone when Shepard killed the Gene Worm. After that, it’s not much of a stretch to think that it could be in the official storyline.

But, it’s really up to Valve to decide that, isn’t it?

Half-Life doesn’t have cannon.

Yes it does…

Oh, I see what you did there.

That’s A cannon. Not cannon. Unless you don’t know English. You do know English right?

Founded in 2004, Leakfree.org became one of the first online communities dedicated to Valve’s Source engine development. It is more famously known for the formation of Black Mesa: Source under the 'Leakfree Modification Team' handle in September 2004.