Familiarity, comfort, basic human psychology.
You'll find some degree of loyalty in any kind of brand whether it's cars or washing powder. We notice fanboyism because games are something we talk about alot, but there is such fanboyism in the car world as well.
A game I'm developing with some friends:
www.xnagg.com/zombieasteroids/publish.htm
It is largely a technical exercise but feedback is appreciated.







