2.5D

2.5D is a style of graphics in video games by which a collection of 2D sprites simulate a partial 3D environment. Many games in the 1990s used this technique, which was so called because although forward, backward and lateral movement was possible, the view could not move in a vertical plane. In early first-person shooters like Doom, it meant the use of 2D character sprites in a 3D world.

See also: Isometric projection

The term also refers to the slight 3D illusion created by the virtual presence of a light source to the left and above a computer monitor. The light source itself is always invisible but its effects are seen in the lighter colors for the top and left side and the dropped shadow to the right and below of such objects as icons in the graphical user interface or GUI.

In machining the term 2.5D refers to surface which is a projection of a plane into 3rd dimension - although the object is 3-dimensional, there are no overhanging elements possible.