Sprites take much size in the executable, so, since we are dealing with basic sprites, I think I could save some kb using ellipses and circles to drawing them on the fly. And I could use some bigger sprites scaling the same definition.
1. Ellipse: (x/a)^2 + (y/b)^2 = 1
2. Circule: x^2 + y^2 <= r^2
Here are the previous and final UFO with this tricky. [Maybe it could be nice drawing the engine flame too]
