You're confusing themes with entire distros.
This is what you want: https://github.com/grassmunk/Chicago95
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You're confusing themes with entire distros.
This is what you want: https://github.com/grassmunk/Chicago95
To add to this, a 'distro' -if you will- that was launched recently with this theme would be the aptly-named Blue95.
Are you thinking of Plan 9?

Tt
I think you're thinking of SerenityOS (although it isn't actually a Linux):
It's worth checking out Blue95, which was originally made as a novelty but has all the power of uBlue behind it, as an opinionated, batteries-included Linux based on Fedora.
Chicago95 XFCE on Debian is my daily driver. Having been a Windows 2000 fanboy, it makes me feel right at home.
The Raleigh GTK theme ported to GTK 3 on XFCE is also a quick and dirty way to get a 90s-esque look: https://github.com/thesquash/gtk-theme-raleigh
For an entire distro, there's Hot Dog Linux: https://github.com/arthurchoung/HOTDOG
There's ReactOS, which is not Linux either and targets the early 2000s Windows versions. Though it doesn't just look like Windows, it's made to be compatible and capable of running those old Windows apps
https://reactos.org/what-is-reactos/
There's also Haiku which has the old Windows look, but prettier imo. It's not Linux, it's based on BeOS, and it's still in beta so not fully usable yet, but it's a pretty cool project
https://www.haiku-os.org/about/
Edit: okay none of those are actually Linux distros so it doesn't really answers the op 😅
Oh, cool! I thought Haiku had stalled out. I guess I was wrong.
Last commit to the nightly build was two days ago so it's definitely still going 😀