Our mining operations in the Asteroid Belt are being attacked by Hostile aliens - Mankind is totally unprepared - we have no space weapon systems to confront the threat. Our only response is the use of our fleet of "Sweepers", powerful craft used to intercept and vaporize small asteroids that threaten our installations. Sweepers were never intended to enter mines - while their plasma cannons are ideal weapons, their thrusters are far too powerful for tight quarters; But we have no alternatives. The SCRATCH simulator will let you pilot a Sweeper to help develop tactics to use against the threat - is defense of our valuable asteroid operations even possible?
Development Notes: This project uses "polar" scrolling - the landscape is represented by 4 segments of the asteroid that rotate about a point off-screen. The ship's motion in x causes the landscape (and things on it) to rotate. Y motion of the ship moves both the ship (by 1/2 the velocity) and the landscape's rotation point (by 1/2 the velocity). This maximizes the "airspace" while letting the ship explore nearly to the center of the asteroid. Shots from the "mines" that are dropped by the flying enemy are controlled by varying their radius and angle to account for the rotation of their reference frame.
Gravity values come from a "look-up" table (contained in a list), that is checked periodically, and a centripetal force value based on the ship's radius and Vx is added to it - the ship can enter a stable orbit.