ToaruOS is a completely-from-scratch hobby operating system: bootloader, kernel, drivers, C library, and user space including a composited graphical UI, dynamic linker, syntax-highlighting text editor, network stack, etc.
United States
openSUSE Alternatives
openSUSE is described as 'Free and Linux-based operating system for your PC, Laptop or Server' and is a very popular Linux Distro in the os & utilities category. There are more than 100 alternatives to openSUSE for a variety of platforms, including Linux, Self-Hosted, Windows, BSD and Mac apps. The best openSUSE alternative is Linux Mint, which is both free and Open Source. Other great apps like openSUSE are Ubuntu, Debian, Fedora and Arch Linux.