This has been interesting, but needed that back story of how Harry ended up on Atlantis.

What about Bigfoot and similar bases...have those been forgotten?

I thought this was pretty good, conceptually and in execution, right up until President ****ing Obama showed up. That was just mind-numbingly stupid. Let's put aside what an evil POS the guy is for a second, and that it sours the entire notion of saving someone when you know that - it just doesn't make any sense in the context of the Stargate Universe, because they do NOT have the same presidents we do in the show. I don't know what year in the SG universe this is because you give no indications, but Henry Hayes is President in 2005, and an actual good guy. Kinsey also becomes president in an alternate timeline. At no point is ****ing Obama president.
Aside from that, there's some hard to understand inconsistencies here. Sam and Daniel are there, and they have (? do they? unclear) the Stargate, I mean they must have since Daniel said that's what its name was - yet they never use it, apparently, even though using it was literally how Daniel got involved with the Military / Cheyenne mountain base. It's really unclear why they didn't just evacuate off world or what the whole thing going on with other civilizations not existing is or why you did that.
That leads to the final critique which is that there's just way too much formalized military speak / orders / communications back and forth, versus a serious lack of actual detail as to what is going on. The fact that I don't even know if they have Stargates and can't understand why they didn't use them tells you that. That's something the reader should absolutely be clear about by the end of the story.
Final point, the entire end right past the President (Obama, omfg, so dumb and immersion breaking, should have let him die! Would be better to have an actual zombie as president!) - it reads like a lazy epiloque you couldn't be bothered to actually write. Show, don't tell, and all that. We don't see a single actual reaction or INTERaction between anyone in the story, we're just told in passing that this, this, and that, all happened and everyone lived happily ever after singing around campfires, basically. Harry building them city ships also flies utterly in the face of the advice we was given and followed earlier about not technologically uplifting them as well - he just did a total one eighty and ignored that later on, for no apparent reason.

This is painful to try and read, honestly couldn't make it more then halfway.

a new paragraph for each new speaker helps readers to tell there is a new person
talking. helps reduce confusion.
another break needed is between locations and universes.

i am realy enjoying story and concept !111

they went to Pegasus 7.5 million years ago and left it 10000 years go

From. the Names are given for the President and His wife I have a. pretty good idea who they are. In the real world, we are distant cousins through my mother's side of the family and his mother. Barack 'Barry' Hussein Obama Barry being a nickname and I know for a while he used his Stepfather's surname which I don't remember right now. And I know my Maternal Grandmother had also used her Step-father's surname for a time as well. Her birth surname was Barwick but her Alias alternate surname with Thomas. The married surname was Weber.

So if You chose to use a real-world former President you caught the attention of one of his distant cousins and I find the situation you put him in a bit funny but yet not. And you mentioned his wife. but yet what about his girls/daughters.

Was there story before this one?

Hi I just read your story zombies way cool.

Really zombies ️ cool

A very interesting start to what promises to be a really good story. I have read quite a number of Crossover stories, and most have been good. It looks like it will likely take a few chapters to get all your main characters and store line fleshed out, but with the hints provided I like where I see this going.

Thanks for sharing!

If they did not immediately start getting data packets from the social satellites that were supposed to exist, then the likely did not get back "home".

Did Harry end up in Atlantis as part of your series, or is this just a stand-alone story?

Yeah, Sam Carter would never say they were not evolved enough to understand something. Understanding things was her thing. Did you ever even watch SG1?

This is decent, but not a favorite. A problem with crossovers is figuring out who's rules win. In this case you had the zombie virus not be fully stoppable, even though with the level of tech Harry had it should have been. Also, I'm not buying they couldn't find uncontaminated DNA. If nothing else you have people buried before the outbreak...