In Parts 1, 2, & 3 we have put together everything, it would seem, besides the actual game. But now we come to the point.

The first set of changes we need to make involve the snake. Instead of a single dot variable, we'll need a snake list . We'll also introduce a variable to allow the snake to grow.

First, modify this line:

dot = pygame . Vector2 ( W / 2 , H / 2 )

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to

snake = [ pygame . Vector2 ( W / 2 , H / 2 )]

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Just above the while loop, introduce the new variable:

grow = 3

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Inside the while loop, we'll make several changes.

A quick conceptual note: Previously, there was a single ("scalar") variable, dot . The animation worked by updating the x and y attributes of dot (via the code dot += vel ).…