Enable the "Debug mode" code and make sure you can be Super Sonic. Gain enough rings so that you will be Super Sonic for quite some time. Defeat Metal Sonic and chase Robotnik and defeat him. When the Death Egg is exploding, and you are running down the shaft to exit, enter debug mode. Change back and run back inside. Robotnik will return and you can defeat him again, however you will be surrounded by fire. When you defeat him again, you will have twice the amount of fire behind when you run out. Note: when this is going on the game will be very slow and you will not actually see Sonic -- make sure you are still Super Sonic when executing this trick.