Borrowing from games

Game interfaces can make software easier to use:
graphical elements
animation
maps
Why borrow the metaphors of games?
The most obvious is that PSDoom takes its interface from a popular game.  Videogames have many appealing features that have been adopted by other applications, such as graphical elements, animation, and maps.

PSDoom is unusual in that it takes the game METAPHOR as well as its interface.  What does this give us?