Once when I was in high school I played Heroes of Might & Magic 3 all day and at the end of the day I felt physically sick. The other time was much later in my 30s when I got addicted to Rocket League and one day I played it all day and again felt physically sick. I used to uninstall it to control my addiction, and once even permanently deleted it from my Steam but later purchased it again. Nowadays and I don't have time and energy for much gaming, I mostly play short sessions.

April 2007 A update for a MMORPG called Dungeon & Dragon Online was release. Guild I was in wanted to be the first on our server to complete the new raid. At one point I was up for over 24 hours straight helping guild members get flagged after I finish flagging my char so that we had enough people to run the raid. We ended up coming in second through. Only 15 min behind the first group to defeat the raid through. We was a smaller server through so most other servers completed the raid before our server. I still had a ton of fun but would never do something like that again. To many other responsibilities these days plus I not sure my body could handle sitting for that long anymore. The timing just happen to be perfect for that particular MMORPG update as it was between graduating college and my start date that I received for my first good paying job. Therefore I was not looking for a job since I had accepted one already and no school.

Depends on what "in one sitting" means. With bathroom and food breaks, I played 19 hours of FFVIII when I got the game for Christmas 99 according to the game's clock. Similarly, I played Kingdom Hearts 1 for around the same length of time on Christmas 02 without sleeping.