Player has to destroy all Enemies spawn in the game. The bullet-enemy collision has been implemented to enable destroying an enemy after gettting hit.Collectible Items
Player can anly move along the Y axis using arrows and he cannot go beyond the screen boundaries. He can fire infinite amount of bullets. Each bullet will move along the X axis until it will be beyond the screen boundary or it will collide with the Enemy object.
Enemies are spawn as a group (EnemyArmy) of objects that move at the same speed and in the same direction simultinously. If the outer Enemy in the group will collide with either bottom or top boundary of the screen the whole group will change direction. The army is constantly moving alonge the X axis and additionally moving Up and Down along the Y axis.
The UI for this game is very simplistic as I just placed current number of Player lives and the current score in both top corners of the screen.