The Pac-Man Dossier is Back
December 29, 2022 9:43 PM Subscribe
The Pac-Man Dossier is an extremely detailed description of the game logic of arcade Pac-Man. It explains why, once in a while, monsters will harmlessly pass through Pac-Man. It explains why they won't go up through the tunnels above the monster box. It explains why occasionally, after losing a life, monsters will refuse to leave the box . It explains when and why Blinky becomes Cruise Elroy, and why sometimes Pinky gets confused and loses track of Pac-Man. It even explains, as far as the player can continue to play, what to do on the kill screen. It is awesome.
I posted the Pac-Man Dossier before, in 2009, but for a while it disappeared from the internet. Then it reappeared, hosted at Gamasutra for a while. It seems to be gone from there now. I think it is creator Jamey Pittman who has since posted it at the address above. It's still the most complete description of the inner workings of Pac-Man, to my knowledge, that there has ever been.
Another related post I had made before is to David Manning's Youtube videos on grouping the ghosts in Ms. Pac-Man.
I posted the Pac-Man Dossier before, in 2009, but for a while it disappeared from the internet. Then it reappeared, hosted at Gamasutra for a while. It seems to be gone from there now. I think it is creator Jamey Pittman who has since posted it at the address above. It's still the most complete description of the inner workings of Pac-Man, to my knowledge, that there has ever been.
Another related post I had made before is to David Manning's Youtube videos on grouping the ghosts in Ms. Pac-Man.
Soon after, however, the ghosts' “blue time” will get reduced to one or two seconds at the most, making it much more problematic to capture all four before time runs out on these boards. By level 19, the ghosts stop turning blue altogether and can no longer be eaten for additional points.
I was wondering why the video of monsters passing harmlessly through Pac-Man seemed so weird. Maybe it was explained in the narration (I watched it while muted and there are no captions)
I've never gotten far enough along to notice the decreasing time, so reading this in the dossier means I'm learning this for the first time.
posted by RonButNotStupid at 8:55 AM on December 30, 2022
I was wondering why the video of monsters passing harmlessly through Pac-Man seemed so weird. Maybe it was explained in the narration (I watched it while muted and there are no captions)
I've never gotten far enough along to notice the decreasing time, so reading this in the dossier means I'm learning this for the first time.
posted by RonButNotStupid at 8:55 AM on December 30, 2022
There is no narration in that video, it's only a gameplay demonstration. It is a pattern devised specifically to show off the pass-through bug.
posted by JHarris at 9:09 AM on December 30, 2022
posted by JHarris at 9:09 AM on December 30, 2022
This is an amazing amount of detail. It's fascinating. It sounds like among other things, they managed to cram a finite state machine into 24 KB of code.
posted by Mr. Bad Example at 12:01 PM on December 30, 2022
posted by Mr. Bad Example at 12:01 PM on December 30, 2022
Of course arcade games did things like that as a matter of course back then, and Atari 2600 games did it with much less to work with. A strong argument could be made, I feel, that programmers now are surrounded with extravangaces of memory and processor power, and that you can do a ton with simple bits and bytes, if you're forced to deal with the machine at that level.
Which isn't to say that today's programmers are bad. Just that programming is hard. Pac-Man's implementors probably spent months working on that 24K, optimizing it over and over.
The thing that I marvel at with Pac-Man's coding is the emergent behavior produced by the ghost's chase routines. Each has a completely different strategy for chasing Pac-Man, that work together very well in creating tension for the player. Especially, the ghosts have to have sufficently different logic that they don't clump together much. A single entity chasing the player is easy to avoid, danger only results if at least two ghosts approach from different directions.
The Red ghost chases directly, so it's usually the fastest to arrive; the Pink ghost chases a little indirectly, aiming for a location in front of Pac-Man, and produces circumstances where it often pins Pac between itself and the Red ghost. Pink's behavior can be easily misled though, so the Blue ghost works with Red to chase significantly more indirectly, but also seeking to make Pac the center of a ghost sandwich. And the Orange ghost is mostly just lurking around the edges, but can get in the way.
I've noticed that a player's learning Pac-Man's strategy tends to enter into situations first where the Red ghost causes problems, then as they develop the Pink ghost, then the Blue ghost, and finally the Orange one.
SOme years ago I made a freeware game called Octropolis (look for it on itch.io if it sounds interesting) that replicates broadly the ghost AI, and includes a few new types, including a Green shark (the game uses sharks for pursuers) that follows the player from a distance, a Yellow shark that tries to get between Pink and Green, and a Grey one that just patrols around the outer edge. I think more work in this direction could uncover even more interesting types of chasing opponent.
posted by JHarris at 12:21 PM on December 30, 2022 [2 favorites]
Which isn't to say that today's programmers are bad. Just that programming is hard. Pac-Man's implementors probably spent months working on that 24K, optimizing it over and over.
The thing that I marvel at with Pac-Man's coding is the emergent behavior produced by the ghost's chase routines. Each has a completely different strategy for chasing Pac-Man, that work together very well in creating tension for the player. Especially, the ghosts have to have sufficently different logic that they don't clump together much. A single entity chasing the player is easy to avoid, danger only results if at least two ghosts approach from different directions.
The Red ghost chases directly, so it's usually the fastest to arrive; the Pink ghost chases a little indirectly, aiming for a location in front of Pac-Man, and produces circumstances where it often pins Pac between itself and the Red ghost. Pink's behavior can be easily misled though, so the Blue ghost works with Red to chase significantly more indirectly, but also seeking to make Pac the center of a ghost sandwich. And the Orange ghost is mostly just lurking around the edges, but can get in the way.
I've noticed that a player's learning Pac-Man's strategy tends to enter into situations first where the Red ghost causes problems, then as they develop the Pink ghost, then the Blue ghost, and finally the Orange one.
SOme years ago I made a freeware game called Octropolis (look for it on itch.io if it sounds interesting) that replicates broadly the ghost AI, and includes a few new types, including a Green shark (the game uses sharks for pursuers) that follows the player from a distance, a Yellow shark that tries to get between Pink and Green, and a Grey one that just patrols around the outer edge. I think more work in this direction could uncover even more interesting types of chasing opponent.
posted by JHarris at 12:21 PM on December 30, 2022 [2 favorites]
ICYDK, from the Pac-Man wiki: "Blinky, Pinky, Inky and Clyde, collectively known as the Ghost Gang..."
posted by VyanSelei at 1:16 AM on December 31, 2022
posted by VyanSelei at 1:16 AM on December 31, 2022
Their "real" English names are Shadow, Speedy, Bashful and Pokey. In Japanese, their names are Oikake, Machibuse, Kimagure and Otoboke, with nicknames of Akabei, Pinky, Aosuke and Guzuta. Pac-Man was mostly a hit in the U.S. though, so the English names are probably the best known.
When talking about the ghosts' AIs, I tend to use their colors, which is what the Pac-Man Dossier itself does. It helps remove confusion, since their names/nicknames aren't always intuitive.
posted by JHarris at 9:10 AM on December 31, 2022 [2 favorites]
When talking about the ghosts' AIs, I tend to use their colors, which is what the Pac-Man Dossier itself does. It helps remove confusion, since their names/nicknames aren't always intuitive.
posted by JHarris at 9:10 AM on December 31, 2022 [2 favorites]
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