The central component of any game, from a programming standpoint, is the game loop. The game loop allows the game to run smoothly regardless of a user's input or lack thereof.
Most traditional software programs respond to user input and do nothing without it. For example, a word processor formats words and text as a user types. If the user doesn't type anything, the word processor does nothing. Some functions may take a long time to complete, but all are initiated by a user telling the program to do something.
Games, on the other hand, must continue to operate regardless of a user's input. The game loop allows this. A highly simplified game loop, in pseudocode, might look something like this:
while( user doesn't exit )
check for user input
run AI
move enemies
resolve collisions
draw graphics
play sounds
end while
The central component of any game, from a programming standpoint, is the game loop. The game loop allows the game to run smoothly regardless of a user's input or lack thereof.