sonic the hedgehog #1 for sega genesis.
stage select- in the sound fx option press sounds 19,65,9,17. hear a bell, hold select when u press start. should bring you to level select.
using the sound fx in the level select, press 1,9,9,2,1,1,2,4. should hear another bell. hold select and press start to choose the level.
you should be able to move to anywhere in the board as well as placing enemies and objects anywhere you feel like it.
as far as i know it only works on the sega genesis version.
if anyone still has this game