A detailed description of my idea:
You control an unknown ‘alien’ entity on its journey of growth and destruction. A full fledged game would begin at microscopic level and end at a cosmic level. Controlling the avatar with your own hand through the LeapMotion. As you roam around you can devour other objects in the scene which are smaller than you, the more you consume the more energy points you gain and larger you get, thus the more objects that are available to consume. While navigating the level you will be required to avoid objects larger than you for they would decrease your energy points making you smaller on collision, you would also be required to figure out what to consume and when in order to progress. An example of this is within the solar system level there are orbiting planets which are relatively smaller than their hosts, you are required to devour the orbiting planets/comets before you have the capacity to consume their hosts and move on to the next stage. The end of each levels sees your avatar consuming the largest object in the scene enabling you to move to the next level, where you would again be the smallest object in the scene working your way to devouring everything. Eventually ending in your avatar being the only thing left and conquering the cosmos.