As someone who got motion sickness playing Doom (and yet still played it to death) I can relate to those who feel sick playing Half-Life 2. Various places
on the net have reports of a sizeable chunk of people suffering nausea and other symptoms from playing Valve's latest
Video games have, for many years, carried warnings about epilepsy and seizure. Is it about time for a "May cause motion sickness or nausea" label?
Just to be different, link goes to Google Groups archive of a newsgroup discussion. Other folk suffering from nausea can be found here.