Your old PC crawls on normal Windows 11, so a light custom build sounds like the perfect rescue. Moon OS is exactly that kind of build - but it is made by the community, not Microsoft. Here is what it really is, what it removes, and how to try it without risking your main machine.
First, one fact clearly: Moon OS is not made by Microsoft. It is an unofficial, community-modified build of Windows 11, based on the LTSC 2024 edition (24H2). The makers took the official Windows image and removed a long list of components - things like Windows Defender, System Restore, Xbox parts, Windows Media Player pieces and many background services - so the system installs smaller and idles lighter. That is the whole idea: real Windows underneath, much less weight on top. This page walks you through the honest install order - test first, back up, then install - and tells you plainly where the risks are, because with any modified Windows, you become your own support team.
Illustration: the smaller footprint and LTSC base are the real facts; the exact numbers on your PC will differ.
A custom Windows install wipes the disk you install it on. There is no undo button, and because System Restore is one of the removed components in this build, there is no built-in safety net afterwards either. So the first step happens before you download anything:
Modified Windows has no live mode like Linux - you cannot try it from the USB without installing. So the safe test is a virtual machine. Install VirtualBox or VMware on your current PC, create a machine with 2 CPU cores and 4 GB RAM, and install the Moon OS image inside it. Use it for an hour: open your browser, your documents, your daily apps. If a missing component breaks something you need - a printer feature, a media codec, an accessibility tool - you will find out here, on a machine that does not matter, instead of after wiping your only PC.
Get the Moon OS ISO only from the source shown in the video, and be careful: for a modified Windows there is no official Microsoft page to compare the file against, so the source is the whole trust decision. Write the ISO to a USB pen drive of at least 8 GB with a tool like Rufus, selecting the GPT or MBR partition scheme to match your old PC. Then restart the PC, open the boot menu (keys like F12, F9 or Esc depending on brand) and choose the USB.
The installer looks like normal Windows setup because underneath, it is Windows setup. Choose the custom install, pick the correct drive - double-check, because the wrong choice erases the wrong disk - and let it finish. On a healthy old PC with an SSD this is quick; on a spinning hard disk, give it time. When the desktop appears, do these three things before anything else:
Treat the first week as a trial, not a commitment. Use Moon OS for your daily work, but keep your backup drive untouched and keep your official Windows USB in the drawer. Try every app you truly depend on - office files, your printer and scanner, banking sites in the browser, video calls. Anything that only lives in a removed component (for example Windows Subsystem for Linux, Xbox/Game Pass features or some media formats) will not work, because those parts are simply not in the build. If the PC feels light and everything you need runs, you have your answer. If something critical fails, you already know the way back.
See the full download, install and first-look walkthrough on screen, step by step, in the video.
Watch Full VideoNo. Moon OS is an unofficial community-made build based on Windows 11 LTSC 2024. Microsoft does not publish it, does not support it, and did not remove those components - the build's makers did.
No. There was an old, unrelated Linux project with a similar name that ended years ago. The Moon OS in this video is modified Windows - your Windows apps and .exe installers run on it exactly because it is Windows underneath.
Yes. A custom build changes the components, not the licensing. Activate it with your own genuine Windows licence - for example the digital licence your PC already holds for Windows 10 or 11.