Titan is a framework based upon Laravel which gives you the tools to quickly build a text based game such as Bootleggers, Torn, Barafranca, even fantasy games such as LoTGD. This of this is a starting point without having to deal with the basics any game requires
Extensions can be anything, a marketplace, bullet factory, PvP, forum. Anything. Big or small. Using Titan gives you a baseline and an easy way to extend a game.