-Final Fantasy 6 ( at the time it was Final Fantasy 3) on the SNES. I rented a lot of games for the SNES as a kid, but once I discovered how an RPG was supposed to be played and got into the story, I kept that game rented for about 2 weeks over a summer. I pretty much sacrificed those 2 weeks to that game.
-Breath of Fire 3. My little brother and I played that game in 3 hour shifts, only giving the system an hour to cool down between play times.