XOR (video game)

XOR
Developer(s)	Astral Software
Publisher(s)	Logotron Ltd
Platform(s)	ZX Spectrum, Commodore 64, Amstrad CPC, Amiga, Atari ST, Acorn Electron, BBC Micro
Release	1987
Genre(s)	Puzzle game
Mode(s)	Single player

XOR is a computer puzzle game created by Astral Software and published by Logotron in 1987 for a range of platforms including the Acorn Electron, Amiga, Amstrad CPC, Atari ST, BBC Micro, Commodore 64, and ZX Spectrum. It has since been unofficially remade for platforms including Windows, Apple Macintosh, Linux, RISC OS, the SAM Coupé, the Game Boy Advance, and Uzebox.

XOR is a pure puzzle game with no random or arcade elements, as summed up by the blurb on Logotron's original extensive advertising campaign:

There are no random events in XOR's labyrinthine palace, and there is no premium on hand–eye coordination. You have all the time in the world to work out the precise nature of the hazards you encounter. Logical thinking, strategy and tactical problem solving are part of the XOR experience. And XOR is not simply about finding solutions. If you can solve the entire puzzle (15 levels plus an encrypted anagram), you qualify to be a member of the Order of XOR.

Gameplay

Objective

The player controls two shields, Magus and Questor, which can be moved horizontally and vertically though the maze, in order to collect masks. The object of each level is to collect all the masks, then reach the exit. In all levels, use of both shields are required for completion, and in some, one shield must be sacrificed (walled in or destroyed) in order to complete the level.

Force fields

In the first level, the only obstacles except for the maze walls themselves, are two types of force field: one of which can only be entered from above or below, and a second which can only be entered from left or right. In both cases entering the force field destroys it.

Fish and chickens

In subsequent levels, fish and chicken objects are introduced. Fish fall downwards whenever possible, while chickens run to the left if not blocked. Both can destroy the player's shields by hitting them from more than one square away (like rocks in Boulder Dash). Fish and chickens can move through force fields if entering from the appropriate direction. It is also possible to push fish left or right, and chickens up and down.

Bombs

There are two types of bombs in XOR: V-bombs ("vertical") and H-bombs ("horizontal"). V-bombs (shaped like jars of nitroglycerin) move left in the same manner as chickens, while H-bombs (shaped like old-fashioned spherical bombs with a burning fuse) fall downwards like fish. Like fish and chickens, H-bombs can be pushed left and right, and V-bombs can be pushed up or down, by the player's shield.

A bomb explodes when it is hit from more than one square away by a fish, a chicken, or another bomb. The object hitting the bomb is destroyed, along with anything directly above or below a V-bomb, or to the left or to the right of an H-bomb. If one bomb hits another, only the bomb that is hit (the lower or left-hand one) actually detonates.

Dolls

Unlike fish and chickens, dolls cannot move on their own, although the player's shields can push them around the maze. Once a doll is moving it keeps going until it hits an obstacle. Dolls cannot detonate bombs or pass through force fields.

Other objects

• Map sections: these reveal the layout of part the maze to the player. Masks are highlighted on the map.
• Frowning masks: these are switches – collecting (or blowing up) one turns off the lighting, causing the maze walls to become invisible, while collecting another turns the lights back on again.
• Teleportation portals (labelled BMUS, for "Beam Me Up Scotty", in some versions): this moves the player's shield to the other teleportation portal within the maze.

Related releases

XOR Designer allowed players to design their own levels. XOR for Schools included six new mazes and a paper planning sheet, intended to be photocopied by teachers.

External links

• XOR at SpectrumComputing.co.uk
• JavaScript XOR version by Rob Veldhuyzen van Zanten
• Windows XOR remake by Ovine by Design
• Game Boy Advance XOR remake by Mick Waites
• Risc OS XOR information site including RISC OS version for download.
• SAM Coupé XOR remake by Howard Price
• XorCurses Linux Linux Curses remake by jwm-art.net
• XorGramana A XOR-like game for Linux using SDL, by jwm-art.net, also implementing XOR.
• Chroma, an accurate conversion of XOR for both Windows and Linux
• [1], "BallBeARing", an updated (2016) 3D version of XOR for Android, with two balls, played also by tilting your device!