HappySqurriel on 21 January 2011
Back in the day I used to get headaches from playing F-Zero on the SNES because of how quickly the backgrounds moved, and I knew people who used to get very dizzy when playing Mario 64 because they became disoriented when navigating a 3D world in game. Over a short period of time people became used to these games (typically after a couple of days/weeks) and the problems went away ... I suspect that any problems with the 3DS will be similar, and by the time the average person has owned it for a couple of weeks they will have no issues with it.
