If youre bored with Quake or would you like to try something new then I recommend you RebirthRO.

RebirthRO is a free mmorpg game and has a long history as a Ragnarok Online private server. Around since 2003, they have some of the longest lasting servers of all time.
They have an incredible Game Master Team, devoted to helping the playerbase, but one that also knows how to have fun.

Their goal is to provide a fun, balanced good time mmorpg game for a great community.

Website - Gameplay Video - Free Download