If you'd like to have a go at making your own asteroids game then you might want to download this simplified version of the above game. It has the spaceship with its realistic motion and it has the five asteroid sprites (which are initially hidden). You will have to create the missile yourself (my program has only one). The motion of the spaceship is realistic because the ship has INERTIA - a tendency to keep going in a straight line. The lunar lander that you saw previously also had inertial behaviour but that was perhaps easier (despite the presence of gravity) because the lander did not turn.

The code to govern the motion of the ship in this program might seem a little hard to understand - I used a variable vx for the horizontal velocity and a variable vy for the vertical velocity. I had to use the trigonometric functions sine and cosine to adjust vx and vy according to the direction the ship is pointing in when the thruster rockets are fired.

I also have code that makes the ship reappear at the bottom of the stage when it disappears of the top etc. That shouldn't be so hard to understand except that I included not only references to the position of the ship but also its velocity just to make sure that there is no 'funny business' like there was with the Pong project.