RPG - Like most have said, I tend to explore and do every possible sidequest before I advance the story. Doing sidequests replaces grinding for me, and I rarely ever grind. Grinding is an archaic RPG device and has no place in modern games. In terms of how I play my characters, I usually try to keep them in specific roles and it's typically based on physical appearance. RPGs usually reward specialists over balanced characters. In battle I stick with physical attacks and skills for regular battles, conserving my MP to go all out with magic on bosses. I also never use items unless it is really necessary, and I never by any items other than status heals for areas where that status becomes a problem.

MMO - I tend to favor classes with a bit of variety rather than standard DD or mage classes. In FFXI I was a Paladin due to the fact that it can tank/do damage/heal and also a Blue Mage since that class was a never ending bag of tricks. I don't mind playing the tank role or DD role but a strict casting role is kind of boring to me. I like having as many different things I can do in battle as possible. I also like classes that have some kind of MP pool or spell casting ability and I favor races with higher MP because that gives me more options.

FPS - I don't really like sniping and I hate melee (it's FPS not FPM). I usually like automatic weapons and my typical strategy is to use cover and then pop out to empty all my clips in a sort of blitz effort. Shotguns work well too: pop out and charge, blowing everything away with one point-blank blast. I tend to favor tank-like characters for survivability since I prefer that over finesse.