To earn this achievement, you need to complete all the levels in the game in one sitting. This means you can't reload checkpoints in case that isn't obvious from the "one sitting" part.
This isn't too difficult once you are familiar with the controls and know how to progress through the levels.
Below are video guides of each level, same ones I have included in the walkthrough. They're not perfect, but they should provide you with a general idea of how to approach this if this is one of the last achievements you need. Just a note however that these are 100% videos, so they're a bit longer as they show you how to get all the achievements in the game. Thanks to the latest updates, you also need to complete the Dark, Steam, and Ice levels. If you want videos for those three, reference the walkthrough.Mansion:Train:Carry:Mountain:Demolition:Castle:Water:Power Plant:Aztec:Dark: