So what are we looking at here? XOR is a tile puzzle, built within a labyrinthine area. The player must take control of two shield shaped tiles, and by sliding them around he must successfully cross all of the blue mask tiles in the labyrinth before proceeding to the exit door. To hinder movement, there are a variety of other tiles which can have the effect of blocking off passages or masks, or can sometimes help to create new passages in the case of explosives. The graphics for these tiles depict artefacts bearing a similar quality, for example: In level one there are wavy lines and spotted tiles which can only be traversed horizontally or vertically, like moving (across) land and submerging (down) in water. In later levels, you can find birds which fly horizontally, bombs which fall vertically, and magnets, dolls and teleports are all introduced, and many other things besides.