The first thing you meet is the Main Menu.
Start a new game by hitting 'Start game' Playing the game depends entirely on the individual missions.
There is, however, some basic rules to the game.
Each levels usually has some goals to fulfill. These can be:
Shoot a number of Asteroids, UFO's
Pick up a number of coins
Rescue a number of Spacemen
Hidden goals (will not be displayed to player)
Shoot a number of Bosses
Shoot a number of Torpedos