Plot: Globulation 2 is a real-time strategy game, available in beta as of January 2009. The game updates on an irregular release cycle and is available in many Linux distribution's package repositories. The game minimizes gaming micromanagement by automatically assigning tasks to units. Wikipedia
Plot: Egoboo is a 3D open source dungeon crawling action role-playing game with support for Windows XP, Windows Vista, Linux, Mac OS X, and some earlier versions of Windows. Wikipedia
Plot: Battle Isle is a series of turn-based tactics video games developed in the 1990s by Blue Byte and released for Amiga and MS-DOS platforms and later for Windows. The settings are wars on a fictional planet, Chromos. Wikipedia
Plot: Chromium B.S.U. is an arcade-style, top-scrolling space shooter available on Windows, iPhone, PSP, Mac, AmigaOS 4, Linux and numerous other UNIX-like operating systems. It is a free software distributed under the Clarified Artistic License. Wikipedia
Plot: Vega Strike is a first-person space trading and combat simulator, developed for Microsoft Windows, Linux, FreeBSD and OS X systems. Many of the core game mechanics of Vega Strike are indirectly inspired by Elite. Other games, such as Wing Commander: Privateer, influenced the original developer. Wikipedia...
Plot: Armagetron Advanced is a multiplayer snake game in 3D based on the light cycle sequence from the film Tron. It is available for Linux, macOS, Microsoft Windows, AmigaOS 4 and OpenBSD as free and open-source software. Wikipedia
Plot: Egoboo is a 3D open source dungeon crawling action role-playing game with support for Windows XP, Windows Vista, Linux, Mac OS X, and some earlier versions of Windows. Wikipedia