They could have bought some crystals, save some crystals, won tournaments or they were given a "Welcome Back" reward or "We miss you" reward for being inactive for so long. I have experienced this kind of reward a couple of times. :) :)

Is this a glitch, a hack, or something else? :huh: :huh: :huh: I have experienced this in a couple of games that I have been playing. These invisible players, especially those who are in the opposing team, can see me but I can't see them. One minute I am cruising along in my tank with a full bar of health and the next minute my health bar starts to drain. My FPS rate is fine and I can see other non-invisible players roam about and engage in combat with hostile players.