Okuplok, often considered the most difficult map made for Doom, was released in 2012. Featuring over 23000 monsters, the map lived for 11 years, never being cleared with 100% kills without the use of mid-map saves on any difficulty.
Six days ago, that changed.
Player "Coincident" set forth on the task of clearing the map without saves, on I'm Too Young To Die. Having never been properly finished, the map itself has no difficulty-based differences; the double ammo pickups and reduced incoming damage on ITYTD may be what makes a saveless "MAX" clear possible at all.
A video of the run can be found
here.