You can get carpel tunnel from playing video games for extended periods of time (with your hands in a bad position). While I was studying over the summer for the bar, my routine consisted of study until midnight, then XBOX or PC games until 4 am. Until your hands strengthen that one little muscle that you've never used but now need to use thousands of times an hour, you will feel some pain, and to counter the pain, you may hold your hands differently, which ultimately leads to actual carpel tunnel.
If you are hardcore, you get yourself some nice wrist braces to prevent the onset or keep it from getting worse (this also applies if you work as a secretary). Lock those puppies in place and game on 'till dawn. Frankly, I don't respect you as a gamer until you own a pair of wrist braces, and / or switched you mouse hand from right to left for a prolonged period of time (days or weeks) due to unbearable index finger pain. And don't tell me "proper posture" blah blah blah. Everyone knows the proper position is slumped on your couch or chair so that you are using as few muscles as possible to conserve your caffeine for your fingers, with maybe enough range of motion to grab your pop and / or salty snack. Of COURSE it's going to hurt, but no pain, no game.