The game is a faithful clone of the Namco arcade game Pac-Man. In development, the game was titled Puc Man (the first Japanese title of the arcade game was Puck Man) but the name was changed before release to avoid legal action. However, the initial release of the game was so close to Pac-Man (including the design of the game's characters) that this version had to be withdrawn and re-released with the characters changed. The player's character became a round yellow face with very short legs wearing a green cowboy hat and the ghosts became skinny humanoid monsters.
As in Pac-Man, bonus items such as fruit would sometimes appear in the centre of the screen. The highest-scoring bonus item was an acorn, a reference to the publishers. When Snapper was killed, he would shrink and turn into small lines pointing in all directions.
The main difference in gameplay between Pac-Man and Snapper is the behaviour of the ghosts (or monsters). In Pac-Man, each ghost has its own personality and follows set patterns for each level. The red ghost also travels at double speed after a certain number of dots are eaten. In Snapper, the monsters begin each level by patrolling their corners a set number of times before breaking from their route to chase the Snapper. The time before breaking the route is reduced for each level until on later levels, the monsters chase Snapper almost immediately. The only real difference between the monsters is the corner they patrol and how soon they break from their route (e.g. the red ghost is always the first). Also, in Pac-Man, the main character slows when eating dots (so ghosts can catch up to him) but this does not happen in Snapper. These changes lead to a game which is much easier in the early levels but gets progressively more difficult so games tend to last longer.
The game ran very smoothly, making it a popular release of the time. As it was written in machine code, rather than BASIC, it was much closer to the arcade version than earlier commercial releases on the BBC Micro such as Micro Power's Munchyman.