Greetings!

Let's get this out of the way: the best system is a system that creates fun. I think that is something pretty much every player of every game agrees on - even if the "how" of getting fun out of a game might vary.

But if we just take that as fact, what does it mean when a game is "good" at something? What makes a system "good" at combat? What is necessary to for one to be "good" for horror, intrigue, investigations, and all the other various ways of playing?

Is it the portion of mechanics dedicated to that way of playing? It's complexity? The flavour created by the mechanics in context? Realism? What differentiates systems that have an option for something from those who are truly "good" at it?

I don't think there is any objective definition or indicator (aside from "it's fun"), so I'm very interested in your opinions on the matter!