Why is a “main” game loop necessary for developing a game?

Question

I find that most game development requires a main game loop, but I don\'t know why it\'s necessary. Couldn\'t we implement an event listener and respond to every user action

Answer 1

A game loop (highly simplified is as follows)

initialise
do
     input
     update
     render
loop
clean up

This will happen every frame the game is drawn. So for games that run at 60fps the above is performed sixty times every second.

This means the game runs smoothly, the game stays in sync and the updates/draws per cycle happen frequently enough. Animation is simply a trick of the eye, objects move between locations but when played quickly enough they appear to be travelling between these locations.

If you were to only update on user input, the game would only react when the user was providing input. Other game components such as A.I game objects would not react on their own. A loop is therefore the easiest and best way of updating a game.