Why do just about no game have real time zombie infections?

Why I acknowledge that several zombie/infection types are slow to develop, others aren't.  Why is it that just about no games have ever shown an infection happen?  Why have we not seen headcrabs in Half Life take over the host either-- they really just attack you? (or do they attach to dead bodies?, can't remember)

Anyway, if you know any games that do so, show a  video.  

Here's my contribution to real time infection:

I think there was an early PSP game that did such a thing. You had to spray your blood on zombies to turn them back to normal, but I think they could do it to you.

I think you do see headcrabs taking over some people near the beginning of HL2. They can't connect to dead bodies since when you kill the body the crab jumps off (I believe).

my god.  Is that the original Metal Slugs or one of the newer ones?  looks...comedic actually.  Not suprising though, metal slug is pretty comedic in generally.

Metal Slug 3. Of course it's comedic, over the top hilarious fun is all it's about.

If you die again, you die for good :P (well, lose a life)

But I think you're at least immune to normal bullets or something like that if you're a zombie. Not the special boss shots and such though, and not immune to more zombies. If you get a pill pick up you revert to normal.

I think it would be cool for there to be an open-world survival horror game where you see a counter in the corner of "Number of People infected" in your town, country, or even the world.

Although I doubt anybody would be able to pull that kind of thing off.

I'm not certain, but I think a real-time transformation is in Extermination.  That's not really zombies though.

Yeah, you really don't see it so often. I do recall those small Flood parasites in Halo will enter bodies and transform into zombies in real-time. I think I've also seen some real-time transformations in at least a couple of the Resident Evil games. Oh, funny. I scrolled up again to your original post and noticed you linked Halo 3 videos. Ha. My PC is going slow so they hadn't loaded the first time I read what you wrote. Guess we're on the same page then. Cool. ;)

I don't think there's really much call for it, I mean traditional zombification is a pretty slow process, it takes hours. If it's something that happens in moment then you are likely to see it on the screen. There are tons of non-zombie like mutations that happen this way though.

I do remember a game where you get bitten, and have a certain amount of time to find a cure before being turned into a zombie, don't remember what it was though and I think you just died instead of turning into a zombie.

Also, another Halo appreciation topic? Wtf.

Edit: Headcrabs attach to live bodies, and you hear it in HL during the raid on the resistance network, but im not sure if you see it or not. Either way, why would you need to? Doesn't make muc sense to me it's needless extra work for the animators when i'd much rather they put the effort into refining something else.

So you're asking why a make believe thing isn't depicted in a realistic fashion?

Biohazard Outbreak did it pretty well in my opinion.

You're infected with it, and what you do can speed it up or slow it down.