In the near future, humans understand that they are not alone...and that's on their very own planet.For thousands of years, the race of the Zonerians lived among simple man and its everyday troubles and happines.The Zonerians are a peaceful race, who settled on Earth a long time ago.The Earth is now threatened of occupation by the 'Black League'.A powerful coalition, the one and only capable of resisting the Galactic Confederation.The Earth is an ancient object of argues, because of its hospitable environment and the 'human resource'! As well as powerful allies humans can also make good slaves.The ancient confilct between the 'Black League' and the Galactic Confederation has now turned into war and the first step will be the conquering of Earth. With the help of their new allies - the Zonerians, humans manage to build powerful laser turrets on the Moon's surface.A team of the best soldiers is sent to 'welcome' the aggressors.You are one of them.Your task is simple: Do not leave an enemy ship come near our planet. The gameplay unrolls onto Moon's surface as it simulates a parallax view over the Earth.The game includes a 5 mission campaign sorted in difficulty order as every mission has its briefing.There is an (almost) unique for Arcade game method of handling players.Every player gathers experience which will rise his/hers character level.The ranking of players depends on each player's experience.