Wikipedia
OpenArena is a free and open-source first-person shooter (FPS) computer game based heavily on the Quake III Arena-style deathmatch. The OpenArena project was established on August 19, 2005, the day after the id Tech 3 GPL source code was released.
Current version is 0.8.8, and an assets "reboot" named "OA3" is planned, with the aim of steering the art style away from the classic space and gothic themes to "something more manga inspired", while also raising its quality and performances standards.
Its official site includes downloads for Microsoft Windows, Linux, and Mac OS X operating systems. Thanks to third-party efforts, it is also available from the default repositories of a number of Open source operating systems, including Debian, Fedora, FreeBSD, Gentoo, Mandriva, Arch and Ubuntu. It is also in development for the Maemo mobile operating system. Ports for Raspberry Pi, Android and iOS are available, too.