It's simple, get from the green tile to the red, whilst clearing the blue tiles in between. This basic gameplay can lead to some very interesting situations though. You must carefully consider the moves you make as you might regret them later; but do it fast because the very ground beneath you is falling!
You can also build your own challenges using the fully featured level editor. Every level I created for the game was in fact created in game with the editor.
This is where things get really fun, you can publish your creations and share them with the world (ala Mario Maker)! Every player created level has its own leaderboard for the fastest times, as well as the ability for players to upvote, favorite, and rate the difficulty of your level.