Crystal Castles has nine levels with four castles each, and a tenth level which features a single castle — the clearing of which ends the game. Each of the 37 trimetric-projected castles consists of a maze of hallways filled with gems and bonus objects, and also includes stairs, elevators and tunnels that the player can use as shortcuts. The three-letter initials of the player with the highest score are used to form the first level’s castle structure. When all gems in a castle have been collected, the player moves on to the next castle. The player can also skip some castles and acquire additional lives and points by using secret warps activated by making Bentley Bear jump at special locations. A trackball and “jump” button are used for controlling Bentley Bear’s motions. Gems are collected by simply walking over them, and a bonus is given upon collection of the last gem. While collecting gems, there are a number of enemies that try to stop Bentley and/or collect the gems for themselves. With two exceptions, if touched by the enemies he will lose one of his lives. Any gems collected by the enemies also result in a lower obtainable score for that screen. Likewise, if the last available gem is collected by the enemy, the player also loses the last gem bonus. Enemies can be avoided by use of the maze and its constructs, or by making Bentley jump over opponents with the jump button, in some cases also allowing him to stun them. Some types of enemies will track Bentley’s movements in certain ways, while others move at random. If Bentley is touched, he “cries out” in a distinctive manner with the use of a cartoonish word balloons. If 3 or more lives remain, he says “BYE!”; if 2 lives still remain, the quotation is “OH NO!”; if 1 life is left, it is “OUCH!”; and finally, for the last lost life (which ends the game), he says “#?!”, so as to imitate an obscenity. At the beginning of every maze, gems are worth 1 point each; this value increases by 1 for every gem Bentley picks up, to a maximum of 99. Each maze also randomly includes a hat or honey pot, which serve the dual purpose of awarding points and providing Bentley with the ability to defeat specific enemies. The hat is worth 500 points and will make Bentley invulnerable for a few seconds and allow him to eliminate Berthilda the witch, who appears in the last maze of each level. The honey pot is worth 1,000 points, and picking it up can delay the landing of a swarm of bees. Other villains present in the game include: “Nasty Trees” which become more ornery as levels progress, a ghost that will usually appear in the Hidden Spiral levels, dancing skeletons, “Gem Eaters” who Bentley Bear can defeat if he catches them while eating a gem, and also the devilish “Crystal Balls” creatures that in later levels tend to follow Bentley Bear persistently as he collects gems. The Nasty Trees and Crystal Balls can also pick up gems. Crystal Castles contains two notable easter eggs. Jumping 100 times or more in the southeast corner of level 1?1 and clearing the maze of all gems will make ATARI appear on level 1?2.[2] On level 5?4, if the player kills Berthilda and goes to the corner of the area where she was and jumps, “FXL” will appear in the southeast corner of the screen. These are the initials for Franz X. Lanzinger, a designer of Crystal Castles.

Centipede is a vertically oriented shoot ‘em up arcade game produced by Atari, Inc. in 1981. The game was designed by Ed Logg along with Dona Bailey, one of the few female game programmers in the industry at this time. It was also one of the first arcade coin-operated games to have a significant female player base, after Pac-Man. The player defends against centipedes, spiders, scorpions and fleas, completing a round after eliminating the centipede that winds down the playing field. The player is represented by a small, “somewhat humanoid head” at the bottom of the screen. The player moves the character about the bottom area of the screen with a trackball and fires laser shots at a centipede advancing from the top of the screen down through a field of mushrooms. Shooting any section of the centipede creates a mushroom; shooting one of the middle segments splits the centipede into two pieces at that point. Each piece then continues independently on its way down the board, with the first section of the rear piece becoming a new head. If the head is destroyed, the section behind it becomes the next head. The centipede starts at the top of the screen, traveling either left or right. When it hits a mushroom or the edge of the screen, it drops one level and switches direction. Thus, more mushrooms on the screen cause the centipede to descend more rapidly. The player can destroy mushrooms by shooting them, but each takes four hits to destroy. If the centipede reaches the bottom of the screen, it moves back and forth within the player area and one-segment “head” centipedes are periodically added. This continues until the player has eliminated both the original centipede and all heads. When all the centipede’s segments are destroyed, a new centipede forms at the top of the screen. Every time a centipede is eliminated, however, the next one is one segment shorter and is accompanied by one additional, fast-moving “head” centipede. A player loses a life when hit by a centipede or another enemy, such as a spider or a flea. The flea leaves mushrooms behind when fewer than five are in the player area, though the number required increases with level of difficulty. Spiders move across the player area in a zig-zag fashion and occasionally eat some of the mushrooms. Scorpions poison every mushroom they touch, but these never appear in the player’s movement region. A centipede touching a poisoned mushroom hurtles straight toward the player’s area. Upon reaching the player’s area, the centipede returns to normal behavior.