The Sun and Moon (EP)

System Three consists of levels 41 - 60 plus boss level III. These levels introduce you to rockets that fly across the screen, and kill you if you touch them. Remember that there is no time limit for completing levels for this achievement, so take your time so you don't die needlessly over and over.

The level structure in System Three isn't anything complex, they've just added rockets that fly in set patterns that you'll have to dodge. Taking levels slow applies more to this system than any other, as you should be extra cautious to avoid the rockets at all costs, and progress in the level only when it's safe. As for the boss, he will drop rockets from above but is very easily avoided. Just make sure to time your jumps appropriately so you don't jump or phase into a rocket. 

Upon completing all 20 levels and boss level III, the achievement will unlock.