What I Learned from 200 Games of Pac-Man, Part 1: Strategy



Few video games are more popular, or more iconic, than the original Pac-Man.  Its arcade version broke records, its AI is practically a YouTube meme, and it introduced one of the most recognizable video game characters in the world.  A deep dive analysis of the game would be redundant with many of the other great resources that are already out there (see the end of the article for some links).  Instead, I decided the best thing to do with this game was to play it -- a lot -- and just talk about what the experience was like.

Background

My previous experiences with Pac-Man were fairly limited.  I owned the infamous Atari 2600 port of the game as a child, but seldom played it.  I may have played the arcade version once or twice in a dentist's office and was familiar enough with it to recognize the approximate layout of the maze, but certainly didn't possess any skill.  It always seemed like a game of quick reaction, more for the body than the mind.  What's more, it didn't appear to me to be substantially different from the countless other variations, including the much-acclaimed Ms. Pac-Man.

So my enthusiasm level was low, at least at the beginning, but slowly I got pulled in.  Here are some of the strategies I developed as I progressed.

Early Strategy

Score vs. Level

My gaming habits are more of the NES age than Atari, so I instinctively shoot for the maximum level whenever first playing a game.  Here's an example of the kind of game I played in my early runs.

Animation of a level of Pac-Man (1980) in which he only goes after the pellets, not the ghosts.

In the first two or three levels, this is a fairly effective strategy because the ghosts spend enough time in the frightened state that they don't have too many opportunities to corner you.  Unfortunately, the power pellets become less scary to them as the game goes on, and you have less time to wander freely.

What's more, ghost avoidance leads to woefully low point totals.  Altogether, the pellets only add up to 2600 points, while even a single ghost chase can yield up to 3000 points, if you manage to get all four ghosts.  I made it as far as level 7 without doing much chasing, but eventually hit a wall in how high a score I could achieve.  So, I decided it was time to experiment with a more aggressive ghost-chomping strategy.

Animation of Pac-Man chomping all four ghosts in the introduction to the 1980 arcade game.

Ghost-chomping

When I started chasing the ghosts, I tended not to progress as far in the game because chasing them forced me to deviate from the optimal paths for pellet-muching.  This would have been easily worth it, if only I could catch the ghosts.  Many of my early adventures in ghost-chomping ended like this:

Animation of Pac-Man in the 1980 arcade version chasing a ghost but not catching it.

It turns out that, unlike the other ghost motions, frightened mode has a lot of randomness built in, so you have to account for the possibility of unexpected direction changes.  This is especially problematic when you're right on their tail because you don't have time to react at an intersection.  There are two tricks I learned to minimize the chances of this happening.

First, it's usually better to come at the ghosts from the front:

Animation of Pac-Man in the 1980 arcade version eating three ghosts by coming from the front.

The advantage of a frontal attack is that you spend very little time at close range, preventing the ghosts from surprising you with a direction change.  There are times when it's better to follow from behind, like when they are at very close range, but usually it will be obvious when this is the case.

The other important tactic is the wait:

Animation of Pac-Man in the 1980 arcade version eating three ghosts after waiting for them to get close.

I generally waited until a ghost was on top of me before eating a power pellet.  That leaves at least one ghost vulnerable for easy munching and brings the others closer.  Ideally, you would have them all in a clump before eating the pellet, but that can require a lot of maneuvering and is usually not worth the risk for non-experts.

Tunneling

The tunnels are invaluable for escaping the ghost swarms in chase mode:

Animation of Pac-Man in the 1980 arcade version escaping the ghosts by using the tunnel.

It is possible for the ghosts to trap you in the tunnel, but this happened less frequently as I gained experience recognizing their patterns.  Also, a successful tunnel passage is doubly rewarding because it tends to concentrate the ghosts, making subsequent maneuvering around the maze less dangerous

Fruit

A transparent image of the all of the fruit in the arcade version of Pac-Man (1980).

Fruit plays a fairly minor role in the early-game action, since they only offer a small point bonus, while leaving you vulnerable to a trap below the ghost cage.  The point bonus increases rapidly, however, and by the time you reach level 7, the ghosts are frightened for such a short period that the fruit becomes the easiest opportunity for a point bonus.

Later Strategies

Traps

There are several locations in the maze where I learned to be especially cautious because I found myself frequently getting trapped by the ghosts.
Pac-Man maze layout with dangerous areas marked, pellets removed, and Pac-Man/ghost images inserted.
The bottom row, in particular, ended up requiring special consideration in my game plan.  The straightaways at the bottom are so long that even if I entered with the ghosts on the other side of the screen, they would still sometimes close in and trap me before I reached the exit.

I found two primary ways of dealing with this.  First, I would look for opportunities to chase the ghosts through the bottom tunnels while they were in frightened mode, that killed two birds with one stone.  The second option was to wait until they entered scatter mode, at which point I tailed Inky or Clyde into the bottom tunnels.

The other trap areas didn't require special consideration, just caution.  The top corners could usually be cleared after grabbing a power pellet and I generally just avoided the central tunnel unless I was trying to grab the fruit.                                                                                      

Misdirection

As I gained experience, I found myself instinctively manipulating the ghost movements through start-and-stop misdirection patterns.  

Animation of Pac-Man in the 1980 arcade version misdirecting the ghosts to enable an escape.

There are no hard-and-fast rules that I was able to exploit with this trick, since it depends on how the ghosts are configured.  When doing a misdirection, keep in mind that Pinky is trying to cut you off, so the direction you're facing matters for guiding her movements.

Invisible Ghost Barriers

After about 50 games or so, I began to notice that there were paths that the ghosts would never travel when in scatter or chase mode.  The one I found most useful was the at the T-shaped junction above the ghost pen.  Ghosts can go down the two tunnels, but not up them, so descending towards the pen is often a good way to escape trouble.

Animation of Pac-Man in the 1980 arcade eating escaping the ghosts by using the tunnels above the ghost cage.

There are also invisible ghost barriers above Pac-Man's starting location, including a "safe spot" in which you can sit indefinitely without being caught.  However, I didn't find this as useful.  At best, it allowed me a momentary respite from the chase.

Pass-through Bug

Okay, I can't honestly say I could consistently exploit this, but it's good to be aware of the pass-through bug when you get into a tight spot.

Animation of Pac-Man in the 1980 arcade version escaping the ghosts by exploiting the pass-through bug.

The pass-through bug occurs when Pac-Man and a ghost are on adjoining game tiles and change tiles simultaneously.  Since they never occupy the same tile at the same time, Pac-Man appears to pass through the ghost.  At high speed, timing this just right is too tall a task for most players, but it never hurts to try.

Summary

Pac-Man is a much more complex game than it appears on the surface.  While you might find it helpful perusing this or other strategy guides, it mostly comes down to actual playing experience and learning to recognize patterns in the ghost movements and configuration.  Knowing intellectually that Blinky finds the shortest path to your position and that Pinky aims four tiles in front of you is not nearly enough to get you through this game.  

However, if you are interested in a more detailed breakdown of the game's history and inner workings, here are some links to get you started:

Gamasutra's Pacman dossier  https://www.gamasutra.com/view/feature/132330/the_pacman_dossier.php
YouTube Video about Ghost AI  https://www.youtube.com/watch?v=ataGotQ7ir8&feature=youtu.be
Gameinternals, a text description of the ghost behaviors  https://gameinternals.com/understanding-pac-man-ghost-behavior
Strategy Wiki with more tips https://strategywiki.org/wiki/Pac-Man

In my next blog entry, I'll review my own experiences with the game, including how my scores improved with time and some experiments with the controls.

Comments

  1. Dear Mr Brow, I enjoy reading your blog but it’s a major pain that you don’t have a proper “next” button, especially when reading through it on a mobile device. Is there a reason for this? Cheers, Will

    ReplyDelete

Post a Comment

Popular Posts