Shred Nebula

Welcome, this one is just like the sonic speed achievement it must be done in one sitting you can't quit I believe there are about 17 levels needs to be completed each level have 5 waves of enemies except the last level it has 10 waves, choose the normal difficulty there is no need make things harder than it should be, the most important thing is you must collect 100% crystals on each level to reach the secret ending level, make your priority is the collect crystals each time at the beginning of every level because sometimes you will forget to collect them while you are fighting the big waves of enemies and if you didn't collect 100% crystals on a level and you advanced to the next level then you need to restart from the beginning and that's happened to me 3 times , this achievement is not hard because even if you lost all your life's you can continue from same level without any problems it just will take around 1 hour and 30 min to be done, the achievement will be unlocked after you complete the last level and before you start the secret ending level so you can skip it if you want but it's good idea to complete it as a respect to the game, anyway that's everything about this achievement good luck.