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Now we're going to move on to something that you'll find in all games: the user interface. The user interface isn't just what keys to press to get the player to move; it's also the opening menu, the configuration screens, and the in-game, onscreen buttons.
Designing a useful, intuitive, and attractive user interface is one of the most important aspects of creating a game. Lacking a useful interface can make a game no fun to play.