Finish the first available act : "Splash Hill zone" act I

Finish the 3 acts of the "Splash Hill zone" and the first "Boss Level" will be available.
Defeat the boss for the first time to get the achievement.

Start an easy act to get the first "Chaos Emerald", I recommend you the "Splash Hill zone" act I. Go to the end of the level while holding at least 50 rings. You will see below the end sign a giant ring. Go trough the giant ring and you will enter the first special stage.
The goal in the special stage is to reach the chaos emerald without touching the red exclamation marks which makes the special level ends (leaving the emerald chaos).

To acquire this achievement you will have to kill 1000 enemies without closing the game in Steam. As each time you restart the game, the counter starts again from 0.

You can play the "Splash Hill" act I again and again until you reach this achievement. It can be tedious as you can kill around 20-25 enemies each time you play the first level. It will take you less of one hour to get this achievement doing so.

Complete the following zones and watch the ending sequence :

• Splash Hill zone
  
• Casino Street zone
  
• Lost Labyrinth zone
  
• Mad Gear zone
  
• E.G.G. Station zone

Please note that special levels are not required to complete this achievement.

To acquire this achievement you should have 99 or more extra lives.
Here are the ways to get an extra life :

• Pick up and grab 100 rings
  
• Collect 3 sonic cards (Casino Street zone acts)
  
• Find an extra life item

An easy way to get this achievement is to play over and over the "Casino Street" act II as you will get a lot of sonic cards in this level.

To unlock the Super Sonic you need to colect the seven Chaos Emeralds.
There is seven different special stages that can only be played (when not unlocked) by a completing an act while holding at least 50 rings and going through the giant ring at the end of the level. Each Chaos Emerald is obtained at the end of each special stage.

I recommend you to start by completing before the hardest acts with 50 rings as the first special levels are very easy to finish. By doing this way you will be able to play again easily the hardest special levels at the end of easier acts.

Note : During a special level, if you are running out of time and haven't touch a red instruction mark, you will be able to press start to pause the game and then restart the special level

To acquire this achievement you will have to complete the "Splash Hill zone" act I under 60 seconds.

This achievement can be done by playing only with sonic, but it will be harder to get. It is recommend to get 50 rings as fast as possible and use the super sonic mode to run faster and reach the goal easier.

You will have to collect all the rings in the first special level : 141 rings

The special levels are available in the map menu once they have been completed once.

To acquire this achievement you have to reach as "Super Sonic" the end of all the acts of the game (except boss fights and special levels).

To transform into "Super Sonic" you'll have to collect 50 rings and then press "Y" (on Xbox controller). You will then be invincible, running faster, jumping higher and breathing under the water.

To acquire this achievement you will need to complete :

• Each act in "Score Attack" mode
  
• Each act in "Time Attack" mode

Note : Press (X) on Map selection screen to switch between "Score Attack" and "Time Attack" modes.

After completing each act in both modes, press (Y) on Map selection screen to go to Leaderboards, then navigate with (RB) through each act. When navigating trough each act leaderboard, the game will upload your current best record for this act.

To acquire this achievement you will have to complete the "E.G.G. STATION" zone without taking any damage. In this zone you will meet :

• The boss of the Splash Hill zone (4 hits to kill)
  
• The boss of the Casino Street zone (4 hits to kill)
  
• The boss of the Lost Labyrinth zone (4 hits to kill)
  
• The second form of the boss of Mad Gear zone (4 hits to kill)
  
• The truly ending boss of this game. This can be a little tricky to not taking any damage.

The Last boss is composed of 4 phases to kill him :

• During the first phase, the boss can be hit by jumping on him (around 20 hits)
  
• During the second phase, the boss is covered by electricity so you cannot hit him directly. You have to hit the arm he throws to you. Then you can hit his body again for a short period of time. (8 hits)
  
• During the third phase, he will be angrier and shot you pink shots. Repeat the same strategy as in phase 2 while avoiding the shots. (4 hits)
  
• During this short phase, you will have to hit him as fast as possible otherwise the "E.G.G. Station" will explode with you inside.