Use Official Virtual Machines: Use software like VirtualBox or VMware to run official legacy versions. You can often find archived versions of early Windows 10 builds on reputable sites like the Internet Archive (Archive.org), which are the actual "Project Threshold" files.
Microsoft skipped the name "Windows 9" entirely. After Windows 8.1, they moved directly to . windows 9 iso
If you are a hobbyist looking to explore the transition between Windows 8 and 10, there are safer ways to do it than downloading suspicious ISOs: Use Official Virtual Machines: Use software like VirtualBox
And if you boot it? The screen just shows: "Welcome back. You’re late." windows 9 iso
Want a more technical or horror-themed version instead?