Beyond entertainment and visuals, the Missed Features Installer includes various system utilities. This includes things like the old Calculator, the classic Windows Photo Viewer, and desktop gadgets. These tools are often preferred for their speed and lack of "bloat" compared to their UWP counterparts.
The installer is typically distributed as a large ISO image (roughly 1.3 GB) and acts as a central hub for various third-party and legacy components. It allows users to add back: Legacy Windows Games: Beyond entertainment and visuals