Linux

FlightGear

macOS, Windows, Linux

Dark Oberon

Linux

Digital Paint Paintball 2

Windows, Linux

Linley's Dungeon Crawl

Disk Operating System, Amiga, Windows, and 1 more

Nexuiz

macOS, Windows, Linux

Alientrap

Bos Wars

Windows, Linux

Tremulous

Windows, Linux

Smokin' Guns

Windows, Linux

Simutrans

macOS, Mac OS, Windows, and 1 more

Hansjörg Malthaner, Markus Pristovsek

Lincity

macOS, Linux

XBill

iOS, macOS, Android, and 2 more

Freeciv

macOS, Amiga, Windows, and 1 more

Marko Lindqvist

World of Padman

macOS, Linux, Mac OS, and 1 more

UFO: Alien Invasion

Linux, Windows

FreeOrion

macOS, Windows, Linux

Geoff the Medio

Cube 2: Sauerbraten

macOS, Windows, Linux

Wouter van Oortmerssen

Neverball

Android, Windows, Linux

Enigma

macOS, Mac OS, Windows, and 1 more

Armagetron Advanced

macOS, Windows, Linux

Frozen Bubble

macOS, Windows, Linux, and 2 more

Unknown Horizons

macOS, Linux, Windows

Chromium B.S.U.

iOS, macOS, PlayStation Portable, and 2 more

GL-117

macOS, Windows, Linux

Blob Wars: Metal Blob Solid

macOS, Windows, Linux

Mari0

Android, macOS, Windows, and 1 more

Freedoom

macOS, Disk Operating System, Windows, and 2 more

Kolf

Linux

Lugaru

macOS, Windows, Linux

Wolfire Games

MegaMek

macOS, Windows, Linux

RARS

Linux