I don't know. I'm left handed, but I never really felt the need to use the mouse with my left hand. I tried for a while, but it didn't feel any more natural than using it with my right hand. I'm quite interested if the left handed people using the mouse left handed actually have a hard time using it right handed, or if it's more of a habit thing (maybe you started left handed because that made sense, and never switched). Otherwise I guess I'm ambidextrous when it comes to mouse use (definitely not when it comes to writing :D ).

I've started using the mouse with my left hand for fun and it reminds me of when I first started using a computer, constantly overshooting what you are aiming for and trying to remember which mouse button does what. It was a bit frustrating in the beginning since you lose the precision you are so used to having. I have also tried playing Mirrors Edge left handed and it wasn't so bad. It was actually the WASD setup that made it hard since it is so awkward to press the spacebar with the pinky.

Al Gore invented WASD.

The DVORAK keyboard layout is the one based on the frequency of letters occurring in use in English. The standard QWERTY layout evolved over time primarily to help prevent keys from jamming on old fashioned typewriters, and allegedly so that salesmen could type the word "typewriter" quickly without knowing how to type (all of the letters in the word typewriter are in the top row). :)

I'm left handed and use the left hand to pilot the mouse - practically the first thing I do with every game I start is access the controls and remap the WASD keys...usually over to the numpad if at all possible, arrow keys if not. The arrow keys are usually isolated a little from other keys, so I have trouble with other functions than move, like jump or crouch. The numpad setup means I have plenty of other keys to assign functions to...

Of course, there are many games which struggle with numpad or just plain dont let you reassign keys - those games i struggle with...

You know, I think there'd be a market for "right-handed" keyboards with the numeric keypad on the left.

Regarding this left/right-handed thingie, I've found it always peculiar that the arcade sticks in coin ops seem to be always (or usually?) on the left side. So it is the opposite how e.g. PC users use a joystick, with their right hand, and buttons on the left. With arcade cabinets, it's the opposite.

EDIT: I had to check it, and I noticed that e.g. for the Gauntlet arcade cabinet, the arcade stick is on the right side. But for arcade games like Tekken 2, Super Street Fighter 2 etc. it is on the left. Maybe it is a Japanese thing?

Dunno if anyone's mentioned this, but way back in the 1980s, on the 8-bit home computers, many games' default keys (if not necessarily in FPS games) were QAZX, up, down, left, right, respectively. With space for "fire" or "jump" depending on the game...

joysticks were....well, the Sinclair ones I had were configured for keys 6-0. Kempston, I can;t remember...

I've started using the WASD layout after playing a lot of...FIFA 96!

Yep, that's right, it was not because of an FPS, but because of a soccer game... i didn't have any joystick/gamepad at the time, and the default keyboard mapping for the game was arrow keys for moving the player, WASD for sprint/shoot/pass/hi-pass

I found that quite confortable so i went on trying with Duke 3D (which i think i had already completed with keyboard only)... when i got to play Quake2 i was actually surprised to see that it was the default layout straight out of the box, and from there never looked back