I.e., games that hooked you in and you couldn’t stop playing until it was finished. Not games that just happened to be unexpectedly short. And by “completed” I guess I mean the main story etc, not 100%ing the game :).
For me, it would be Catherine, Bioshock Infinite and Black Mesa (although I think I got to the final area then had to go to sleep and complete it the next day). I also played an ungodly amount of Hades in one sitting, but didn’t get the “full” ending in one day.
God of War on Ps2. I remember starting in the morning and finishing when it was dark outside. In fact I think I skipped eating and not even using the bathroom. I remember rushing to the toilet after beating it since my bladder was about to burst hahaha