XOR presents the challenge of 15 brickwork mazes through which the player searches for masks, clearing each maze of masks before progressing to the next.
Clues can also be found in the form of map sections which show the maze you're in and the uncollected masks. Some routes are blocked by barriers that cannot be penetrated; other barriers can be broken through by the shield you operate. But none-of these obstructions appear on the map screen -and the number of moves on each level is limited.
Further dangers await on higher levels. Springloaded chicks can pin you to a wall, dolls and fish fall when a supporting shield or shelf is removed, bombs explode and poison pits offer uninviting swims.
On exiting each level, you receive a letter, when all 15 letters are collected, they form an anagram which can be solved to give a clue to XOR's true nature (Logotron's words).
'XOR's graphics are very simple, but it's addictive and the presentation is slick. It's a lot like a larger version of Cavelon, a very early Often game. Toggling between two characters - if you can call them that when they're only shields - is supposed to make your task easier, but it doesn't a bit. The only useful feature is the map that shows where all the uncollected masks are hiding, and because the screens are all basically the same it soon gets very boring.'
'XOR is a puzzle game in the genre of Survivors, it's well difficult, but becomes quite playable with perseverance - some of the later levels are much too tricky for me, though, so I gave in a fit of rage. The simplistic large characters and a fast but disconcerting scrolling routine leave little impression; I'd advise a few goes before buying.'
'Despite poor scrolling, XOR isn't as bad as it might first strike you; the graphics are big and quite colourful, and the gameplay soon grows in attraction and addlctivity.'