A player runs a space ship loaded with different weapons. The ship can fly both vertically and horizontally within the borders of the game screen. At the beginning of each level the space is empty but during the flight certain enemy ships and obstacles appear on the screen. Enemies can fly freely on the screen making tricks and special moves. The purpose of the game is to kill as many enemy objects as possible, including asteroids. After a certain number of enemy objects is destroyed a player gets different bonuses, i. e. healing packs, weapons upgrades, double-power packs, etc. When the enemies are eliminated on the level, a player jumps to the next level. After completing every three levels you’ll meet a super-boss on your way – an enemy super space ship with tricky weapons and fight behavior.
The game offers many guns from common machine gun to plasma gun and ion shell. Homing missiles find targets themselves and help annihilate super tricky enemies.
Launched as GRAIL A and GRAIL B in September 2011, the probes were renamed Ebb and Flow by schoolchildren in Montana. The probes operated in almost circular orbit near the lunar poles at an altitude of approximately 34 miles, until their mission came to an end in December 2012. The distance between the twin probes altered a bit as they soared over areas of lesser and greater gravity that were caused by visible topological features on the Moon's surface, such as impact craters and mountains--as well as by masses that were secreted beneath the lunar surface.
In fact, it may be much more reasonable to suppose that the American government's real capabilities in space exceed anything we have heard about, or can easily believe.
Earth's mysterious large Moon is our nearest neighbor in space, dominating our clear night sky with its beguiling and bewitching cold golden glow. Earth's Moon is the only body beyond our planet that we have visited, leaving our footprints embedded in its alien dust. Despite its close proximity to our planet, our mysterious Moon has still managed to keep some ancient secrets from us very well. However, in October 2014, using data derived from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission, a team of planetary scientists announced that they may have solved a lunar mystery almost as old as our Moon itself.