January 2016
February 2016
Using Energy has become common practice in mobile games. You can go to almost any game of this genre and have this exact same style of play, though they may call it something other than "Energy."
You restore 1 Energy every 6 mins. You can also spend Crystals to get a boost of 120 Energy.
Crystals can be earned through game play and you can also purchase Crystals outright from the in-game store.
Though, for any game you play, you should probably play the game a little bit and get a good handle on flow of the game before getting upset at someone else for your lack of understanding of a free product that you chose to spend money on.