Fallout(yes the first one) played it through repeatedly, last playthrough I eradicated everyone, after achieving maximum level minmaxed as the ultimate energy weapons user, armed with a turbo plasma rifle and the alien blaster, wearing hardened powered armour, nothing could face me and hope to live(except the vault 13 overseer, who as far as I can tell is invulnerable). That gaming session was interspersed with breaks only to collect food from the refridgerator, and use the toilet periodically as needed, and lasted for somewhere over 3 full days, not sure when I finally fell asleep, all I know is that I woke up on the floor next to my chair... so over 72 hours, not really sure of the exact length of time.
That was a long time ago.