I play Team Fortress 2. It is a mediocre arena-style first-person shooter game. It's not a bad game, of course, and it actually has quite a few innovative things going on for it, but it plays and seems a few releases too old compared with what is out there now.
However, the main benefit it has is that it's free. At one point it was sold as part of the fabled Orange Box (which also had the classic Portal and one of the Half-Life games). Now it is free to play and download, and they make money off of microtransactions (i.e., buying small and cheap items, often, and by lots of players).
The game has a nice sense of humor and doesn't take itself too seriously. Even if you don't intend on playing the game, you should check out their promotional trailers on YouTube (Type in "Meet the" and one of the classes below. The Medic in particular is fun to watch.)
Anyway, I've been playing it for a few months now, and I realized quite too late that I kind of suck at the game. I still have fun, but as with all online games, there are a lot of folks out there that take the game WAAAY too seriously and do not like the fact that I can barely hold my own while in comat.
Anyway, the list below gives an overview of how to play each class. This is probably only amusing to those who play the game, but still.
What I Should Be Doing: Using speed as an advantage to get point-blank shots and hit-and-run maneuvers.
What I End Up Doing: Getting slaughtered by sentries and rockets while trying to pull off some lame trick with Mad Milk or the Holy Mackerel.
What I Should Be Doing: Committing long-range attacks and positioning explosions to maximize damage
What I End Up Doing: Killing myself by shooting the payload in error at close range.
What I Should Be Doing: Burning down rivals and checking for spies
What I End Up Doing: Running straight at opponents and getting mowed down before the flamethrower gets in range, and never changing this tactic for any reason whatsoever
What I Should Be Doing: Bouncing bombs off of walls for sneaky indirect hits
What I End Up Doing: Bouncing bombs off of walls so they bounce right back at me, and repeatedly doing it as if somehow that is going to change.
What I Should Be Doing: Mowing down rivals and absorbing massive amounts of damage to help my teammates.
What I End Up Doing: Eating sandviches out in the open.
What I Should Be Doing: Strategically placing buildings to hide from enemies and help my teammates.
What I End Up Doing: Finding the exact spot to have a sentry destroyed two seconds after building it up to level 3.
What I Should Be Doing: Healing my teammates
What I End Up Doing: Failing at bumping up my Strange Syringe Gun's kill record.
What I Should Be Doing: Standing in the shadows and picking off unsuspecting combatants.
What I End Up Doing: Lying face down in a pool of my own blood with a dancing Spy on top of me.
What I Should Be Doing: Backstabbing opponents and frying sentry guns.
What I End Up Doing: Getting slaughtered the moment an enemy sees me despite the fact that I am cloaked or disguised.