Start off with a text file.  Line 1 is the text description that appears at the start of the level.   This may be different to the main level name.. Whatever you wish.
The next 100 lines should be 100 characters long.   To start with, they should be all 0's.   You can copy + paste the following text into Notepad, if you wish.

Now, using "Overwrite" mode, (hit Insert key) you can "draw" your level on the map using the following ASCII characters.

0 (or space!) Nothing...

# Wall.  The game will automatically make the walls look a little neater (i.e. sorting out the angles of adjacent walls) when it loads the level.

8 Red Player Start

9 Blue Player Start

$ Moving Flame Start

£ Stationary Flame

1 Vertical Pipe

2 Horizontal Pipe

3 Pipe Junction.  Use junctions for corners, and the like. (see "Pipe Building" section later.)

6 Red Barrel

7 Blue Barrel

A-Z (capitals) Boulders.

a-z (lower case) Remotes for Boulders.

- (minus) Holes for Boulders.  Place beside boulders.  You can even make paths to move the boulders along, but I couldn't think of a reason to do that, so I didn't make any myself!

[ Red Block.   Allows only the Red player through.

] Blue Block.   Allows only the Blue player through.

 

And.. um... Don't let the player go over the level-boundary, I couldn't be bothered adding detection, and the game crashes.. !

 

Pipe Building

When designing Pipe layouts, keep the following things in mind.

If the player hits a Junction block, they will do the following.   Check ahead 1 block, if there's a straight line, carry on.  If not, check Clockwise, and then Anti-Clockwise, before resorting to turning back.

The following Pipe layouts will result in the following actions.  (In all cases, player is moving upwards, from the bottom)

Layout Result
  1 
  1 
  3 
  1 
  1 
Player will continue in an upwards direction.
  1 
  1 
  322
  1 
  1 
Player will continue in an upwards direction.
  1 
  1 
223 
  1 
  1 
Player will continue in an upwards direction.
    
    
  322
  1 
  1 
Player will turn to the right.
    
    
223 
  1 
  1 
Player will turn to the left.
    
    
22322
  1 
  1 
Player will turn to the right.
   1
2233
  332
  1 
  1 
Player will turn to the right.  Useful for 4 way pipes.
 1  
 3322
233 
  1 
  1 
Player will turn to the left.  Useful for 4 way pipes going the other way round!