For level select go to main select and select either Sonic 3 or Knuckles. Play the first level (Angel Island) as any character exept TAILS. As you get into the level you will find some vines that you swing on, grab onto one of the vines and while you are hanging press, LEFT, LEFT, LEFT, RIGHT, RIGHT, RIGHT and then UP, UP, UP..You should hear a ring if this works!! Now press ALT R to reset the game, when at the title screen, press down until you come to sound test, select it to go to the level screen. The sound test won't work, but the level select will!!
Hint: 99 lives
In Zone 6, Act 1, go to the first Flybot Alarm and perform a Spin Dash, favoring the right half of the alarm, and hold it. If lined up correctly, the Flybots will keep appearing. Eventually you will start getting 10,000 points for each Flybot. Keep doing this until you get 99 lives.
Note: depending on how many lives you need to get to 99, you may surpass the time limit.
Sound Test
Enable the "Level select" code. Restart the game using the option under the "File" menu. Press (Down) (Down) at the title screen.
Play as Knuckles in Sonic 3
Choose Sonic 3. Enable the "Level Select" code. At the level select screen, choose Special Stage 1 or 2. At the "Get blue spheres" screen, press Enter. If you start as Sonic, hit the Red spheres. The Spinning star should be red. Press Alt+R to restart the game. Choose "Sound Test". Choose a zone and act (except the Sonic & Knuckles zones). When it starts, you will be Knuckles!!!! You cannot beat the game or fight robotnik where Knuckles usually fights in Launch Base Zone Act 2.
Getting Rings on the special mode
Minimize the screen(It should already be minimized when the game coms on.)then go up to game and click on the Special Mode. After you do that, Play with any charector(there should olny be two)and go to the first set of Blue spheres(When the stage is on)then go around in a squre and the spheres should turn into rings.