SCP Foundation

I like your writing and tone. Clinical and to the point. No major issues I see with that.

SCP-OOOO is a computer program compatible with Microsoft, Apple, and Hewlett-Packard computers and nearly all forms of available software.

I'm not quite sure what you mean by this. Do you mean the program only works on computers made by those companies, or that it is compatible with Operating Systems commonly found on those model computers? You mention it is compatible with all forms of available software, so I assume you mean any operating system, as other software isn't really necessary to run a program by itself. I would suggest clarifying what you mean; maybe just state that it runs on any computer, regardless of operating system or hardware specifications.

SCP-OOOO can only be downloaded from an external source4 and has not been discovered to be available on any known internet platforms.

You say that it can only be downloaded from an external source, but what if the Foundation uploaded it for testing? Would someone be able to download it then? I would also suggest you move the discovery up to the description and cut it as an addendum; people probably want to know where it came from if it's from an external source.

Upon doing so, the program will close and a series of anomalous psychological activity will begin to develop within the

subject. A timeline of anomalous activity is displayed below

It doesn't reflect it on the quote box, but you've got a bit of a wonky formatting on this section right. Go back to your draft and check if that is intentional or not.

weeks after anomaly start:

The wording on this is a little awkward. I'd suggest re-writing it to something else. Perhaps:
"weeks after initial exposure". Just a suggestion.

continue investigation on the accusation of SCP-OOOO.

I'm not quite sure what this means. Are you referring to the hospital being accused of creating or using SCP-OOOO? I'd suggest a rewrite just for that sentence to make it clearer.

Only other thing I noticed is you forgot to capitalize "Foundation" in the discovery addendum.

I actually really like this. I'm not quite sure whats going on, but its interesting, and the symptoms are non-malicious enough to be a refreshing change of pace.

I do feel like it ends rather abruptly. The build-up of the stages are nice, but I felt like it ends before reaching its peak. As I don't know what is really happening, I can't suggest anything, but I do think maybe brainstorming some other ways to escalate it might be worth it? Unless that messes with your intended vision, in which case ignore that. I just felt a tad let down when I reached the final stage and realized that was it.

The other thing I have a complaint over is the discovery and background of this thing. It's my assumption that this thing was being used by the hospital for use on their patients, but I feel like this isn't really that interesting. Maybe it was uploaded online at a singular point, and there is some backstory behind the guy who created it and why he did so? Just some suggestions, since I do feel like this aspect is probably the weakest part of the SCP.

Overall, I did like the concept, I just feel it needs a little work to fully capitalize on it.