This is how I think of it:
If you have an array that is 40000
Then that can be thought of as a grid 200 by 200
Now if the player Position variable Subtracts 200 at once thats Forward one space
If the player Position moves 1 number More thats to the Right one space
Adding 200 is Backwards
And Subtracting 1 is Left
You could use this in a rouge-like with text tiles, a game with sprites or a 3d environment. I have done all 3 to some extent.
// Create a number array of 40000
DIM worldGrid(40000)
// Create a string also known as a text array of 40000
DIM worldTextGrid$(40000)
// Create a space with a Wall
LET worldGrid(800) = 1
// Set where the player starts
LET playerPosition = 1200
// Move The player up one space
LET playerPosition = playerPosition - 200
// Make the player bounce back so the wall is like its solid
IF worldGrid(playerPosition) = 1 THEN
LET playerPosition = playerPosition + 200
END IF
// Move The player right one space
LET playerPosition = playerPosition + 1
Just change the numbers to the correct 200 or 1 and operators to + or - for the other directions.
There are many ways to show this information with a little effort, ideas and testing. Like a text adventure describing you walked forward, back, right, left or hit a wall. Also you could show it with sprites or on a text-tile based map(Rouge-Like).