Quake is a very customizable game.
Not only can you create new levels, weapons, and sounds for Quake, you can also develop entirely new games, such as Quess and Quake Rally . Even ignoring these settings, there are lots of features you can adjust within Quake to customize your playing experience, such as the skill level, the way you control the character, options for deathmatch play, etc. A front end provides a simple interface for organizing and setting these options, giving you more time to worry about not getting killed by an opponent rather than worrying about which command allows you to look up and down with your mouse. In the future, if you want to play Quake with those same options, rather than doing all the work of repeating the commands, you can simply tell QuakeOn to start the game with those settings. After you build your library of QuakeSets, you never need to worry about all of the commands again.