Atari 2600 Crystal Castles is one of the first arcade action games with an ending, instead of continuing indefinitely, looping, or ending in a kill screen, and to contain advance warp zones.
Crystal Castles gameplay
Crystal Castles has 9 levels with four castles each, and a tenth level with 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, a tune of the Nutcracker Suite is played, and the player moves to the next castle.
A trackball and jump button control Bentley Bear. Gems are collected by 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. 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 Bentley leaping opponents via 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 and loses a life, he “cries out” in a distinctive manner with the use of a cartoonish speech balloon. If at least 3 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 start of a maze, gems are worth 1 point. This increases by 1 for every gem Bentley collects, up to a maximum of 99. Each maze includes a hat or honey pot, which serve the dual purpose of awarding points and letting Bentley defeat specific enemies. The hat (500 points) makes Bentley briefly invulnerable. The hat also allows him to eliminate Berthilda the witch (3,000), who appears in the last maze of each level. Picking up the honey pot (1,000) can delay the landing of a swarm of bees.
Other villains include Nasty Trees which become more aggressive as levels progress, a ghost that will usually appear in the Hidden Spiral levels, dancing skeletons, Gem Eaters whom Bentley Bear can defeat if he catches them while eating a gem, and Crystal Balls that appear in later levels and tend to follow Bentley Bear as he collects gems. The Nasty Trees and Crystal Balls can also pick up gems.
The player can skip some castles and acquire additional lives and points by using secret warps activated by making Bentley Bear jump at special locations.
Crystal Castles contains two 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. On level 5‒4, if the player kills Berthilda and goes to the corner of the area where she was and jumps, “FXL” appears in the southeast corner of the screen. These are the initials of programmer Franz X. Lanzinger.
(source: Wikipedia)