A shape-game can be played on DGS as an unrated game with an arbitrary setup of white and black stones. A saved shape can be used to either create a new game in the waiting-room or send an invitation to another player.
 
Shape-games are marked with the -icon on various pages with a goban thumbnail of the shape if you hover over the icon, and linked to the definition of the particular shape.
 
To find shape-games in the games lists or in the waiting room, you can use the Game-Type filter with "Shape-Games" (to only show shape-games) or "No Shapes" (to exclude shape games).