If you want to get a quick boost up the screen, or you've messed up a jump and think you're in danger of falling off the bottom of the screen, tap on Ralph to send him soaring into the sky. That will use up some of his soda meter though, and you'll need to collect the little bottles in each level to top it back up again.
Atlas is an action-rpg with rogue-like elements where you use your ability to control the ground to fight the enemies and move through procedurally generated worlds.