Sonic 2 is a fun game which is worth playing.
The game plays as your average platformer with an emphasis on speed. Your two playable characters are Sonic and Tails - though they play exactly the same, Tails was a brilliant addition to the series and is my favourite Sonic character. You can play as either Sonic or Tails alone. But you can also play as Sonic and have Tails follow you. The computer controls Tails and he can be handy because he can pick up extra rings and help hit bosses for you. A second player can pick up the controller and play as Tails if you chose to play in this way.
There are a total of 10 zones overall each with two acts (there are some exceptions however) Each zone is uniquely themed. There's a chemical plant, hill top, casino area, factory and an airship. MOST of the levels play the same though in my opinion. Some levels have gimmicks to help them feel unique, such as Casino Night having pinball tables and Aquatic Ruin (and Chemical Plant Act 2) having underwater sections.
The game feels quite long, but for the most part is relativity easy. In the levels you zoom at high speeds through the level, bouncing off enemies and springs, avoiding obstacles, doing deadly leaps across pits and running like a roller coaster across loops. At the end of the second act there will be a boss battle. These are generally quite easy and don't require much skill. Overall the stages are fun to play.
If you pass a star post checkpoint with fifty rings or more, a spinning star circle will appear. Jump into it and you will be taken to the special stage. There are seven special stages in total. Basically you are in a half pipe with a 3D perspective. Your goal... pick the stated number of rings up whilst moving on rails and dodging bomb formations. The later special stages are quite difficult. If you are playing as Sonic with Tails following you, the amount of rings you have to collect will be increased slightly. Tails makes these stages harder when he follows as there is a delay on his actions so he will smack into bombs and loose rings. For your efforts you are rewarded a Chaos Emerald. If you are playing as Sonic, collect 50 rings, press jump twice in a row and see what happens. Tails users however, get nothing.
There is also a two player mode where players can race each other to the finish. Player one will control Sonic and Player two will control Tails. There are four zones to select from in this mode. This includes the special stage where the winner will be the one who collects the most rings.
Graphically the environments have a very solid colour scheme and look bright and pleasing to look at. The graphics are slightly better than those seen in Sonic 1 as there is more colours on sprites and the game looks brighter. Musically the game is good. The tunes are good to listen to.
So Sonic 2, as stated in my classification, is worth playing. It is quite long so you will need patience to complete it without using cheats. It is very easy to pick up and play so almost anyone should be able to play this and get reasonably far without much difficulty. Pick it up if you see it.