Circus was one of the first games produced by Exidy that used a CPU (6502) to control the game logic instead of hand-crafted hard-coded logic circuits. It ran on a black & white monitor with a color overlay that gave each row of balloons at the top of the screen a different color. It was designed and programmed by Edward Valeau and Howell Ivey of Exidy in 1977.
Circus came in an upright dedicated cabinet, and may have also been available in a cocktail configuration as well. Circus machines had white sides with red painted sideart of several balloons in flight. The front of the machine was decorated with a large ornate monitor bezel that also doubled as a marquee (or nameplate). This bezel showed several clowns in a circus scene and had the game title spelled out with multicolored balloons. The control panel was unadorned, save for an analog spinner and a start button. The whole machine was finished off in black T-molding.
At least 13,000 units, possibly as many as 20,000, were produced.
Zork is one of the earliest interactive fiction computer games, with roots drawn from the original genre game, Colossal Cave Adventure. The first version of Zork was written in 1977–1979 using the MDL programming language on a DEC PDP-10 computer.
Colossal Cave Adventure is a text adventure game, developed originally in 1976, by Will Crowther for the PDP-10 mainframe. The game was expanded upon in 1977, with help from Don Woods, and other programmers created variations on the game and ports to other systems in the following years.
In the game, the player controls a character through simple text commands to explore a cave rumored to be filled with wealth. Players earn predetermined points for acquiring treasure and escaping the cave alive, with the goal to earn the maximum amount of points offered. The concept bore out from Crowther's background as a caving enthusiast, with the game's cave structured loosely around the Mammoth Cave system in Kentucky.
Haunted House is one of the 12 original games that were shipped with the Magnavox Odyssey system. It runs on Cartridge No.4 and uses clue cards with an overlay.