Core Wars

Core War

A game of Core War running under the pMARS simulator
Original author(s)	D. G. Jones & A. K. Dewdney
Initial release	1984
Type	Programming game

Core War is a 1984 programming game created by D. G. Jones and A. K. Dewdney in which two or more battle programs (called "warriors") compete for control of a virtual computer. These battle programs are written in an abstract assembly language called Redcode.

At the beginning of a game, each battle program is loaded into memory at a random location, after which each program executes one instruction in turn. The object of the game is to cause the processes of opposing programs to terminate (which happens if they execute an invalid instruction), leaving the victorious program in sole possession of the machine.

The earliest published version of Redcode defined only eight instructions. The ICWS-86 standard increased the number to 10 while the ICWS-88 standard increased it to 11. The currently used ICWS-94 standard has 16 instructions. However, Redcode supports a number of different addressing modes and (from ICWS-94) instruction modifiers which increase the actual number of operations possible to 7168. The Redcode standard leaves the underlying instruction representation undefined and provides no means for programs to access it. Arithmetic operations may be done on the two address fields contained in each instruction, but the only operations supported on the instruction codes themselves are copying and comparing for equality.

A number of versions of Redcode exist. The earliest version described by A. K. Dewdney differs in many respects from the later standards established by the International Core War Society, and could be considered a different, albeit related, language. The form of Redcode most commonly used today is based on a draft standard submitted to the ICWS in 1994 that was never formally accepted, as the ICWS had become effectively defunct around that time. Development of Redcode, however, has continued in an informal manner, chiefly via online forums such as the rec.games.corewarnewsgroup.

Warriors are commonly divided into a number of broad categories, although actual warriors may often combine the behavior of two or more of these. Three of the common strategies (replicator, scanner and bomber) are also known as paper, scissors and stone, since their performance against each other approximates that of their namesakes in the well-known playground game.