It was 1998 i was playing some games, biomenace or duke nukem, and i learned how to memory hack some DOS games

BUT I can´t remember the program name nor how it worked, wanted to know if you remember it.
From what i remember of it was something like this:

you enter the game with lets say 5 lives, and you search for 5 in the program
you loose 1 life, enter the program again and search number 4
you gain 1 life, enter the program and search for number 5
etc etc

till the program found the exact memory area and you could enter whatever you wanted, thus making the character invincible.
same thing with ammo and other stuff.

does anyone remember the programs that let you do that?