Level codes that really work:

To warp [HUGO SAYS xx] (xx is level number)
To enter level editor: [THE FINAL CUTX]

     Here  are the passwords for levels 20 to 40 (the first 19 are too
easy).  But  if  you  can't  be  bothered to type them in on the title
screen type 'ELOWANTS' followed by the number of the level you want to
go to. Enter the password THE FINAL CUT or ABRAKADABRA to get into the
construction kit.
                                                                            
20 Other things         27 Falcons flight       34 Veni vidi vici           
21 Be honest            28 Blue angel           35 We like it               
22 Blue in violet       29 Far thunder          36 Forever here             
23 Three paths          30 A simple one         37 Wonderland               
24 Dangerous            31 Blue velvet          38 The snare                
25 The wanderer         32 Paradise 1           39 Cure it
26 Secret chamber       33 Classic art          40 Sun is shining