1. Programming:

     To  get  through  the  game with all of your lemmings still alive
open  the  SAVE.DAT  file  with  a  Hex editor. Find the position that
starts  C8 Hex. Change the Hex code to 3C to save all of your lemmings
and to 03 for first place. The file starts with the number of lemmings
saved  skips a position and then shows the position that you finish in
so  an  edited  file  that  places you in first place with all of your
lemmings would look like this:

3C 00 03 00 3C 00 03 00 3C 00 03

     The file ends at position 2CE Hex. Always remember to back up the
SAVE.DAT file before you start.

2. Cheat:

     Here  is  how to play any of the 120 levels in the game: Edit the
l2.ini  file in the lemmings directory by typing: edit l2.ini [Enter].
This opens the l2.ini file for editing with the DOS edit function (DOS
5).  Take  the  cursor down the bottom of the file and type: Cheat = 0
(note the C of Cheat must be a capital letter and the rest of the word
must  be  in  lower case with a space either side of the = sign). Save
and  quit  to  DOS. Now load up Lemmings 2 just as you would normally.
When  the  title screen appears select the 'prefs' icon. When the menu
appears  there  should  be an extra heading called 'cheat mode'. Click
the cursor on that and then return to the menu screen Play the game as
normal  -  but you can now select any of the 120 levels to puzzle your
way through.