For the better part of 44 years, Nintendo's 1981 arcade classic Donkey Kong was understood to have a single, definitive endpoint: a "kill screen" where a bug ensures that Mario will inevitably die before you can complete the level. But now speedrunner Kosmic has figured out that this supposed kill screen doesn't have to be the end.
The original arcade version of Donkey Kong takes place across four stages that loop in various configurations of increasing difficulty. Those loops are displayed in-game as levels, and once you reach level five the difficulty has essentially peaked - you just keep repeating the same loop over and over again.
Excellent Donkey Kong players register their high scores in level 22, which is where the kill screen occurs. The bonus score timer overflows - Kosmic's video below goes into much more detail on how this bug works - leaving you with just a few seconds to clear the stage. That's not nearly enough time to get Mario to the top of the screen, so you simply die here over and over until you run out of lives.
The kill screen occurs on the barrel stage, which requires you to climb up a bunch of ladders and run across several slanted girders to reach the end. But there's actually another path to the end - an absurdly precise trick that lets you take advantage of a glitch to climb up a broken ladder all the way to the top of the stage.
Players theorized that this ladder glitch could be used to beat the kill screen stage before the timer runs out as far back as 2013, but the timer still wasn't quite long enough to let you beat the stage, even when creating what amounted to a tool-assisted speedrun. But Kosmic wasn't aware of that fact when he started testing the theory, and his own TAS worked. He climbed up the glitched ladder and beat the kill screen.
What changed between 2013 and 2025? Nothing more than simple chance. Donkey Kong's timer isn't actually a consistent clock, as it instead ticks down each time the titular gorilla rolls a barrel at you. These barrel tosses happen at essentially random intervals, and if you happen to get really, really lucky, the delay between the throws will slow down the timer long enough for you to execute the glitch and climb to the top of the stage.
"In order to have time to beat the kill screen," Kosmic explains in the video, "you need [Donkey Kong] to do a pretty good initial delay, which he'll do about a third of the time. Then you need to roll a 1 in 32 chance that he does an additional long delay. And that's assuming you play perfectly."
Hitting those odds at the end of a grueling, multi-hour high score attempt would be troubling enough, but successfully executing the ladder glitch under those conditions would effectively be impossible. The ladder glitch requires you to hold down for four frames, then tap up on the next frame. A human speedrunner can certainly do that trick once, but executing it over and over again fast enough to climb this broken ladder before the timer runs out would be functionally impossible.
"Let me be clear," Kosmic asserts. "This will not happen for real. To make it to the top you need to do the broken ladder climb trick 90 times, and that's not just getting the inputs 90 times in a row. You have to do them as fast as possible, back to back, perfectly. If this is still sounding even remotely possible to you let's just consider the sheer speed of it: you need to do 12 of these climbs per second."
The only way to do that would be precisely programming your inputs into an emulator, which is essentially what Kosmic did to finally get past the kill screen. There are a few more stages past there, before the timer once again becomes too short. This time, however, time runs out on the rivets stage, which has now equivalent glitch to bypass. For now, this is the "true kill screen" of Donkey Kong.
There is, in theory, one way you could get past the old kill screen without making a TAS of your own. Those delays between Donkey Kong's barrel tosses could, in theory, continue indefinitely, giving you enough time to beat the level normally without even needing to do the ladder glitch. Kosmic estimates that the odds of this happening are around 1 in 40 octillion.
