The January 29th, 1996 release of Duke Nukem 3D or Duke3D for short. (…) Duke Nukem 3D was the first commercial implementation of a new engine known as BUILD, developed by Ken Silverman. BUILD featured an editor that had a real-time What You See Is What You Get (WYSIWYG) interface, meaning that level designers could lay out a level in two dimensions, then immediately switch into a 3D mode to see what the level would look like. Previous editors and engines required the map to be compiled and then run in the game engine in order for level designers to see the progress of their work. This innovation significantly reduced the turn around time for level design, and also made the process much more intuitive.
Besides making level design easier, BUILD allowed Duke3D to have an unprecedented amount of interaction with the world. (…) Duke 3D and BUILD allowed level designers to add in, for lack of a better term, special effects that gave the player the illusion that they were dramatically effecting or altering the game space, when in reality they were merely triggering the special effects that the level designers had pre-placed. (…) In addition to the influence players could have on the geometry of the level, Duke 3D also added in the ability to destroy or interact with a large number of in-game objects. Fire hydrants could be smashed, urinals interacted with, coke cans exploded, and so on. Practically any decorative object could be destroyed, resulting in a shower of debris, adding realism to the firefights.A History and Analysis of Level Design in 3D Computer Games Sam Shahrani