Spacer is a puzzle game played in the first person, alike to the Portal series. The player is given not a portal gun however, but a 'space capturer'. The 'space capturer' takes a 3D space in front of the player, captures it into a 2D surface, and a wall is created in its place. This surface can be then placed on a wall, at which point the captured space is moved to the position of the wall.

The objective of the game is to reach the exit, which is initially inaccessible. The player must capture specific areas that may for instance include a staircase or an elevator. When placing these in the correct location, the exit can be reached.

An interesting use of this 'space capturer' is when it captures a space horizontally, but is placed such that the space becomes vertical. This could be used if the exit is below or above the player. At all times, the exit is highlighted through walls so that the player knows where to head.

Image source M. C. Escher, retrieved 1/08/2016 from https://fineartebooks.wordpress.com/2012/04/19/when-art-intersects-with-mathematics-constantin-brancusi-m-c-escher-and-cristian-todie/