I've played a few games for about 10 hours straight with a couple bathroom breaks, snack breaks, and stretch breaks. So not exactly hardcore no breaks, but a long time without doing anything else for longer than 5 minutes.
Probably way back when Rome Total War came out, so about 2004. One weekend(School Half-Term) I played it for about 16 hours, from the afternoon to the early hours of the morning. Yeah, never again will I do that. Now that I have work I only really play for a few hours here and there. But sometimes on Friday nights, or Saturdays, I'll play CoD for a few hours with friends.