An interesting game.

Energy is an interesting Incremental Game, in that it has a strong foundation in Idling, yet still requires fairly frequent attention. The break-point between painfully slow and lighting fast is reached quickly, and once you've crossed it, the game takes on a life of its own.

There is a constant attention-sink in the form of your ship's energy, and with no way so far to idle that (although the capacity can be increased), the game will demand you pay it a visit once every few minutes or so.