Posting this on the weekend because it's long. But it's worth it if you're a Doom fan.
Okuplok was a huge Doom 2 slaughter map from 2012 with a whopping 23,211 monsters (including 166 Cyberdemons). It was also never really finished or balanced[^1], and proved impossible for anyone to beat without cheating, even on the easiest mode.
Until a few months ago, when Coincident, one of the best Doom streamers, finally pulled it off.
I've watched it at least three times since it came out (usually in chunks), and if you ever played Doom, it's amazing to watch someone take on wave after wave of monsters in groups that would kill an average Doom player in a second (or at least would kill me). Just one of the most insane Doom runs I've ever watched.
[^1}: The creator left the Doom WAD scene because there were also accusations of him cheating on his speedruns, if I remember correctly).