Open Quartz was an attempt at creating a free content replacement for the original Quake, similar to Freedoom. It is primarily tailored for Deathmatch using the Darkplaces engine, which includes FrikBots (press end or pageup) and a selection of arenas and character models, but features one single player level with killer trees only vulnerable to explosives.
The project was started in 2001 and was last updated in 2004, despite a couple of attempts at a continuation. A project called Haktoria was also attempted for Hexen II, which also used the Quake engine. A philosophical successor, LibreQuake, was started in 2019. The game is released under the GNU General Public License.