Due to the tremendous popularity of Pac-Man in the arcades, and the arcade operators' insatiable appetite to cash in on the craze, bootleg arcade manufacturers produced a number of unauthorized copies and alterations to the original game. It wasn't enough to try and sell a straight clone of the original game. Bootleggers competed with each other to create the most flashy modification that would attract more players. Most changes were purely cosmetic, altering the maze, or the looks of the characters, and some changes altered the point values for pellets, prizes, and eaten ghosts. Many of the changes included in some of the bootlegs below inspired some of the changes that were incorporated into an official Bally Midway release of Pac-Man Plus (which was third Pac-Man title in the series to have been created without the authorization of Namco).
 New Puck-X
- The name of this bootleg is a play on one of Namco's other arcade games that was popular in Japan during the early 1980s, New Rally-X.
- New Puck-X contains a fairly altered maze. Bumps have been added to the center of the rows at the top and bottom that were wide open in the original. Holes have also been added to the portions of the maze around the regenerator and the bottom that were solid in the original.
- There are two extra sets of tunnels in this maze, one at the top above, and one at the bottom below, the original tunnel. Meanwhile, greater access has been given to the center tunnel, so you could be ambushed by ghosts from the sides before you have even reached the tunnel.
- Regular pellets are worth 20 points and power pellets are worth 80. Bonus items start with Cherries which are worth 500 points, and are worth 5000 points by the time you reach the Galaxian Flagships on Round 9. The Strawberries (Round 2) are worth 700 points, the Oranges (Rounds 3 & 4) are worth 1000 points, and the Grapes (Rounds 7 & 8) are worth 2000.
 Pac-Man (Hearts)
- This bootleg is called Pac-Man (Hearts) by MAME. It is primarily French, and is also known as "Newpuc1" or "Scandleman" by some players.
- Newpuc1 uses the same maze format as New Puck-X, including the extra sets of tunnels. All of the pellets have been changed into the shape of hearts.
- When Pac-Man eats a power pellet, rather than turning blue, the ghosts all change into a shape that can normally be seen during the third intermission of Pac-Man, when Blinky is running away, with his pelt dragging behind him. They are the same color as the hearts, and they will flash red when the power pellet is about to wear off.
- Hearts are worth 20 points and power pellets are worth 80. While the first three ghosts are worth the normal amount of points (200, 400 and 800), the fourth ghost, if eaten, is worth 8000 points, compared to 1600 points in the original.
- There are two different maze variants in Newpuc2. The first is a visible blue maze, similar in format to New Puck-X (shown left). However, it increases the height of the bump along the bottom row, and adds four sets of escape tunnels to the original one rather than just two. The second maze is invisible except for the outer walls (and the pellets), but has a slightly different layout from the visible maze and has only three sets of tunnels on each side (shown right).
- As in Newpuc1, when Pac-Man eats a power pellet, rather than turning blue, the ghosts all change into a shape that can normally be seen during the third intermission of Pac-Man, when Blinky runs away with his pelt dragging behind him. Unlike Newpuc1, however, they remain their original colors until they begin to flash before returning to normal shape.
- Intermissions from the original Pac-Man arcade game appear between each maze. A "slot machine" appears every three rounds, which determines which type of maze (visible or invisible) will come next.
- Hearts are worth 20 points and power pellets are worth 80. Like Newpuc1, while the first three ghosts are worth their normal amount of points (200, 400, and 800), the fourth ghost, if eaten, is worth 8000 points. The bonus items start at 1000 points for the Cherries, and work their way to 5000 from there.
- "Hangly-Man" is presumed to be an "Engrish" mangling of the title "Hungry Man".
- Hangly-Man contains not just one, but two different mazes. The first maze (shown left) appears on the first round and every even-numbered round thereafter. The second maze (shown right) appears on the third round and every odd-numbered round thereafter.
- The first maze is an alteration to the original maze. While an extra bump has been added to the once-open bottom row, the top row has been opened up. The areas near the mouths of the escape tunnel are no longer single width tunnels, but more open. This can cause players to miss the tunnels if they are not lined up exactly right.
- The first maze also contains two extra sets of tunnels, one each above and below the original tunnel. Eating a power pellet in the first maze can sometimes make it become invisible. In some versions of Hangly-Man, this maze will never reappear until you die, so you should remember the maze's layout.
- The second maze is a wide-open maze, with no outer walls except around the very edges. The same three sets of tunnels exist, as well as a new tunnel, that has been positioned along the center of the top and bottom of the maze, similar to Piranha (see below).
 Pac-Man (Galaxian hardware)
This is a hack of Pac-Man where the programming of the game is made to work on the hardware of a Galaxian machine instead of the original hardware. Galaxian is an older game, and therefore not quite as capable of displaying the game properly. When a ghost is eaten, and returns to the ghost regenerator, you see everything except for his eyes. The number of lives you have remaining and the number of the current round are displayed on the left and right sides of the screen, and the ghosts are introduced by their "alternative" names, from the original Japanese version on the title screen: Urchin/Macky (yellow/brown eyes), Romp/Micky (red/blue eyes), Stylist/Mucky (red/black eyes), and Crybaby/Mocky (purple/yellow eyes). Presumably, this bootleg was created and purchased by the arcades primarily due to its lower cost, or operator naivety.
- Joyman drastically changes the designs of both Pac-Man and the ghosts, to a more abstract-looking yellow character, and various colored cyclops (only referred to as "Red", "Pink", "Blue", and "Orng Monster"), respectively. (The eyes have naturally been turned into a single eye.)
- Joyman also contains an altered maze, changing the colors and the arrangement of the alleys. The alleys are arranged more like columns.
- There are pellets, that straddle several of the alleys. While the pellets are present, and as long as Joyman does not die, he can continue to pass through the gaps in alleys. However, if Joyman dies, some of the gaps close upon his return when restarting at the centre of the maze.
- The bonus prizes and the music have also changed. Pellets are worth 20 points and energizers (small checkered flags) are worth 80 points.
- This hack of Pac-Man was released as a conversion kit. It was only available as an upgrade board, much like the original Ms. Pac-Man was.
- The graphics have been drastically altered to present an underwater theme. You control a red piranha, while you are chased around by four squid-like monsters. (In an earlier variant of the game, they are little more than altered ghost sprites, with extended sprites for the tentacles).
- Most of the maze in the game is wide open. You're free to move about various open portions of the maze, but so are the squid-like monsters.
- One central tunnel is present on the left and right sides of the maze, as well as another central tunnel at both the top and bottom of the maze.
- There are fewer bonus items, and their values start at 500 points for the Crab, and end at 5000 points for the Yellow Anchor. Eating the squid-like monsters is also worth four tremendously different point values: 300, 700, 1200, and 2000 points, which adds up to total of 3200 points.