Donkey Kong killscreen overcome after 44 years
For four decades, more than 117 rounds were not possible in the original Donkey Kong. But it is possible, although hardly for human players.
The player "Kosmic" on a Donkey Kong machine, but he cracked the kill screen using TAS.
(Image: YouTube/Kosmic)
Just over a week ago, a player with the pseudonym "Kosmic" achieved what had been considered impossible in the Donkey Kong community for decades: he beat the kill screen of an early arcade version of Donkey Kong using frame-accurate input in an emulator. To understand why this is a significant event in gaming history, we need some background on the game itself and the technology of historical 8-bit systems.
Donkey Kong was Nintendo's first global success and was released in 1981 as a slot machine with a CRT screen. The company not only defined the genre of the platform game, but also established the principle of a game character with recognition value, despite having only a few pixels. In Donkey Kong, the player controls a character known only as "Jumpman" at the time, who later became Mario, who would jump on every subsequent Nintendo platform and later drive go-karts.
The limits of early 8-bit systems
Because hardware, especially RAM, was still relatively expensive in the early 1980s and players were expected to put as many coins as possible into the machines, the games were extremely difficult by today's standards. Separate memory areas for code, graphics, sound and the frame buffer were also rare; all the processor(s) used was a shared RAM and the ROM in which the game was stored. These ROMs were later read out so that the original code of the machine could also be played in emulators.
Donkey Kong's new gameplay and difficulty made it extremely attractive in 1981, even for competitive players. Various companies also organized tournaments for these players, and it quickly became apparent: You can't play further than 117 rounds. In Donkey Kong terms, this corresponds to level 22-1, i.e. the first round of the twenty-second difficulty level. For comparison: casual players rarely get beyond level 4 or 5, even on the original hardware. The order of the individual tasks doesn't change after level 5, everything just gets faster and more random. Nintendo obviously didn't think that anyone would get further than level 5.
Empfohlener redaktioneller Inhalt
Mit Ihrer Zustimmung wird hier ein externes YouTube-Video (Google Ireland Limited) geladen.
Ich bin damit einverstanden, dass mir externe Inhalte angezeigt werden. Damit können personenbezogene Daten an Drittplattformen (Google Ireland Limited) übermittelt werden. Mehr dazu in unserer Datenschutzerklärung.
However, because players quickly developed strategies against the game, partly due to random generators that were not really random, round 117 was already reached in 1982. Incidentally, this takes over an hour and a half. At this point, the game behaves completely differently than usual: the countdown for the remaining time to complete the round runs seemingly unpredictably fast, showing confusing numbers, and after eight seconds Jumpman dies, even though he has not been touched by an object or opponent. This is the "kill screen" in this game, because the player is apparently killed by a mysterious force. There is of course a bug behind this, more on that in a moment. Unlike the "Rebirth" of Tetris on the NES , which was also only recently overcome, Donkey Kong does not restart, the player dies, the match is over, back to the start screen. Pretty frustrating.
250 plus 10 is 4
The kill screen occurs reproducibly in round 117 because the counter for the time the player has for a level is saved as a single 8-bit value. The number of bonus points credited for unused game time is derived from this (among other things). The value increases with each round, at round 116 it is 250 decimal, at round 117 it would be 260, which does not fit into 8 bits, it ends at 256. So there is an overflow, and the actual value in RAM is 4. This results in the 8 seconds in the bonus points formula.
Videos by heise
The original Donkey Kong, or more precisely the arcade ROM "US set 1", can therefore only be played beyond round 117 if you make it to the top of the screen in 8 seconds, the goal of every round. But how can you do that in this time? Kosmic, who is known for speed runs, i.e. particularly fast playthroughs, now had a solution. He used an emulator and tools that can repeat inputs frame by frame via software. The new record is therefore a "tool assisted speedrun" (TAS). In many communities, this is not cheating, but a discipline in its own right. Kosmic is also good with the original machine, reaching the kill screen without tools.
It also takes a lot of luck
When overcoming the kill screen, Kosmic used the "ladder glitch", a bug in the game in which Jumpman climbs further and further up a ladder after a tricky input – even if there are no ladders in the corresponding places. With this bug, Kosmic beat round 117, and then played on for several hours - usually frame by frame. At round 122, level 22-6, it really didn't go any further, the time could not be kept even with the "ladder glitch". Together with some of his colleagues, Kosmic continued to analyze the code and the runtime behavior of the game. They found out that he was already very lucky on round 117. There is another random factor that provides half a second of extra time with a probability of 1/32. Kosmic and his helpers have written down exactly how this works and many other details here.
In his YouTube video, which has now been viewed over 1.4 million times, Kosmic also explains that he does not consider – to be humanly possible, even with the half-second extra – round 117, because the "ladder glitch" can only be exploited by moving the joystick up and down exactly 24 times a second for every movement of Jumpman. A player would then have to repeat this exactly for the entire 8.5 seconds. And then, in a real playthrough without technical assistance, he would already have around one and a half hours of jumping and bouncing in his fingers.
(nie)
