Notes about Pac-Man

pac-man game design

  1. When the game starts, the player needs to make the decision of going left or right, all the levels are the same in terms of structure, the only difference between choosing left or right is determined by the AI of the ghosts.
  2. There’s an area surrounding the spawn of the ghosts that doesn’t have points to collect, as it’s a ‘dangerous’ area.
  3. The only ghost that is outside of the ghost box at the beginning is the red ghost, Blinky, this ghost has the most aggressive AI behaviour, it might be outside the box because of maintaining symmetry (3 ghosts, there’s a middle.)
  4. The energy spheres are power-ups, they give more points when you collect them, the power up state allows you to momentarily ‘eat’ the ghosts so you have more time to eat the points. There are only 4 energy spheres per level, they call your attention by blinking.
  5. You and  the ghosts can wrap around the level by moving through the tunnels at the sides of the level.
  • There’s some kind of coyote time that allows you to turn even if you’re technically exceeded by some pixels.
  • When you eat a ghost, or you’re eaten by a ghost, time stops for a moment, stopping time for a moment is a game feel ‘technique’ that’s used in some games in things like combat or platforming, although generally with not the amount of intensity (or frozen frames) that Pac-man has.
  • The ghost AI is based directly in the movement of Pac-Man, in special cases, by ‘random numbers’, this makes it possible to win the game just by following a choreography of movements.
  • The ghosts have a defined name, color, and a personality given by its AI.
  • There are 3 states that the ghosts have:
    • Chase: Where the ghosts target Pac-man and hunt him
    • Scatter: Where each ghosts target one corner of the level (each ghost with a specific corner) and loop around for some seconds, this state is the state that the ghosts are in at the beginning of the level as well, it’s an important feature as it gives the player some seconds of calm and room to breathe.
    • Frightened: When Pac-Man eats the power-up, the ghosts tend to give an 180º degree turn and run away from Pac-man.
  • The time each stage lasts gets modified depending on the level, becoming harder (scatter mode lasting less and chase mode being longer, Pac-man speed increases and ghost speed increases) at higher levels.
  • The ghost AI is roughly like this in chase mode:
    • Blinky (Red): Targets Pac-man and tries to find the shortest path to him every time Blinky enters a new tile.
    • Pinky (Pink): Targets 4 tiles ahead of Pac-man, tries to catch him from ahead.
    • Inky (Sky-blue): The target is defined first by an offset of two tiles depending on the position and orientation of Pac-man, and finally by a vector from Blinky through that offset point and then doubling the length of the vector.
    • Clyde (Orange): Targets Pac-man, but enters scatter mode for a moment if he gets 8 tiles near Pac-man.

For a more detailed information on Pac-man:

The Pac-Man Dossier (https://pacman.holenet.info/)
Pac-Man | Design Icons (https://www.youtube.com/watch?v=S4RHbnBkyh0)
Pac-Man Ghost AI Explained (https://www.youtube.com/watch?v=ataGotQ7ir8)

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