RISC OS is described as 'Risc OS is an open-source OS specifically designed to run on the ARM chipset' and is an app in the OS & Utilities category. There are more than 100 alternatives to RISC OS for a variety of platforms, including Linux, BSD, Self-Hosted solutions, Windows and Mac. The best alternative is Ubuntu, which is both free and Open Source. Other great apps like RISC OS are Manjaro Linux (Free, Open Source), Arch Linux (Free, Open Source), Windows 10 (Paid) and Fedora (Free, Open Source).
Chromium OS is an open-source project, used primarily by developers, that aims to build an operating system that provides a fast, simple, and more secure computing experience for people who spend most of their time on the web. Chromium OS and...
BunsenLabs Linux is a distribution offering a light-weight and easily customizable Openbox desktop. The current release is Helium, built on top of Debian (stable). The project is a community continuation of CrunchBang Linux.
MINIX is a POSIX-compliant Unix-like operating system based on a tiny microkernel running in kernel mode with the rest of the operating system running as a number of isolated, protected, processes in user mode.
antiX is a fast, lightweight and easy-to-install linux live CD distribution based on MEPIS and Debian's testing branch for Intel/AMD x86-compatible systems. antiX offers users the "Magic of MEPIS" in an environment suitable for old computers.