Sin and Cos are a programmers best friend! I was looking at other games for inspiration and I saw this image from r-type
A circle of aliens spins around the player and you have to shoot them from the inside.
To calculate the points of a circle is quite easy, the calculation is -
Therefore I have an array of 10 objects which is calculated as follows -
230 pixels from the 'origin' and I have 10 objects - 360/10=36. I is incremented by 1 each step.
I now have a nice circle of aliens, I can increase the number by reducing the number 36. I can make the circle smaller or larger by increasing the radius.
The first level is more or less complete, with boss monster at the end. On to the second level!