gMars are game earned resources. gMars are used to place towers on the map and upgrade tower parts with more uses coming in the near future. Players are required to have purchased at least 1 loot box before they may begin to earn gMars. gMars are unlocked after clearing wave 15 on Very Easy. (This # is only for very easy difficulty) The amount of gMars dropped per wave clear and the guaranteed drop rate vary based off the difficulty setting.