You can get Crystals for unlocking achievements and clearing the territory around your camp.
Sometimes we give free crystals if the player has discovered a new bug. The one that was not known before. The player should attach a video where the bug is reproduced as the proof of his discovering and send it to our support channel.
You can contact our support by using Support button in the Settings. If your game hang or not responding for some reason, you can press 4 fingers to your screen and in 5 seconds you will be directed to create email for our email@example.com