This is a thread showing off some of the cheats and a mission guide for Sonic 2 : Secret rings edition.
So, first of all are the missions.

Normal - Play the game as it was originally meant to be. (With some extras of course)
Hands Off - Finish the stage with no rings. This mission was called too easy by many people, so the "No Rings" mission was created.
Diehard - Finish the stage without dying at all.
Perfect - Finish the stage without getting hit. This applies even if you have a shield.
Stealth Attack - Finish the stage without attacking any badniks.
Super Sonic - Start the stage in Super form, and make it to the end without losing the status. You will start off with a set amount of rings. Here, the ring drain that normally accompanies the transformation is much faster, however the Shield and Invincibility monitors now provide extra rings.
No Rings - Do not collect any rings at all. This mission is very, very hard to complete.
Escort - Finish the stage without losing Tails either by him dying or being off the screen for too long.
Rampage - Destroy all the badniks in the level.
Ring Collection - Collect a certain amount of rings the stage will set for you.

Now the cheats. These will be entered on the sound test in options.

If you enter 20 09 04 13 in the sound test, you will be warped to the Hidden palace zone, and to get instant level 99, enter 20 08 03 10.
WARNING : Level 99 will raise your speed VERY high, and your acceleration. So watch out - this speed is only half of Sonics true speed, and you can't control it.

That's me done!
~Pikachi~

nice review i enjoyed reading it. i hope people who play this game get help from this thread