I have just remembered an old cheat for the Mega Drive/Genesis (CARTRIDGE!!!) version of Sonic 3D! it's an alternate way to open up the level select! When you load up the game, wait for the "produced by or under license for Sega Enterprises" message to dissapear. now any time between the SEGA logo and the title screen, tap the cartdrige softly (or hard, whichever takes your fancy. BUT NOT TOO HARD!). You should be taken to a blue screen reading "Congratulations! You have found the Hidden Level Select!", or failing that, a blank screen. if you got a blank screen, reset and try again. THIS DOES WORK, I remember trying this when I used to have a Sonic 3D cartdrige and heard about this cheat! this is a bit quicker and easier to do than entering the code in :P Try this if you have the game in cartdrige form, and let me know if you had any success!