Following the success of Pac-Man, Ms. Pac-Man, and Super Pac-Man, Bally-Midway decided that they would release yet another Pac-Man game. The problem was how did they keep the Pac-Man concept fresh while still staying close to the gameplay of the original? The answer? Jr. Pac-Man! Although it might not be immediately obvious, Jr. Pac-Man is supposed to be the son of Mr. and Ms. Pac-Man and is not the same character as Pac Baby from the cartoon series (Baby Pac-Man was a whole separate game).
Jr. Pac-Man was the natural sequel to Pac-Man and Ms. Pac-Man (I hope she's Mrs. Pac-Man now), and as such expanded on the classic Pac-Man formula. Jr. Pac-Man adds several new enhancements to keep the tired old Pac-Man formula interesting. Unfortunately some of the new features made for a very VERY difficult game. In fact most gamers consider Jr. Pac-Man to be the hardest Pac-Man game of them all (Baby Pac-Man not withstanding).
The first and most obvious enhancement is the scrolling maze. Now mazes can fill several screens which leads to new patterns and strategies. However since there is no radar in Jr. Pac-Man, players need to remember which parts of the maze they've already cleared. Thankfully the Atari 5200 handles this scrolling beautifully with no jerky motions. You'd think with a larger maze to hide in that the ghost monsters would have a harder time finding you, but you'll soon find out that this is not the case.
The next major enhancement was the addition of giant dots. Giant dots are made from normal dots after they come in contact with the bonus prize. While giant dots are worth more points than regular dots (50 vs 10), they slow Jr. down and make him more vulnerable to roaming ghost monsters. For this reason it's best to stop the bonus prize before it makes too many giant dots or Jr. may find that he doesn't have the necessary speed to outrun a pursuing ghost.
The last enhancement is perhaps the most deadly. Now roaming prizes destroy power pellets when they come in contact with them! There's nothing like running towards a power pellet with a gang of ghost monsters in hot pursuit only to see it destroyed moments before you reach it. It's best to grab prizes before they move too far or you may regret it later. Of course the ghost monsters will constantly be hot on your tail so Jr. will have to figure out if it's worth putting himself in danger to save a power pellet or if it's best to just let it go.
Although conversions of Pac-Man and Ms. Pac-Man for the 5200 were decent but nothing extraordinary, Jr. Pac-Man really shines on the 5200. About the only major thing missing from this version are the intermissions between levels which were cut for space reasons. While Jr. Pac-Man was actually developed for all three of Atari's systems at the time (2600, 8-Bits, and 5200), only the 2600 version made it out and even then it was delayed for three years due to the crash. Although the 5200 version may look complete, the last known version still needs some polishing and uses sounds from Ms. Pac-Man as placeholders. Interestingly a complete version for the 8-Bits (dated 7/10/84) has been discovered which not only has unique sounds, but adds the ability to select the number of ghost monsters in the game (while removing the teddy bear level). This means that the a complete 5200 version must also exist as the 5200 was the original and the 400/800 was the conversion. To date this more complete 5200 prototype has not been found.