Space Invaders requirements

Modified Game Description
Earth is under attack from rows of bomb dropping aliens, and you need to defend it! The rows of aliens begin at the top of the screen, and you control a laser cannon that moves back and forth under cursor control at the bottom of the screen, and, also under keyboard control, fires laser shots at the aliens and their bombs. Your goal is to earn points by shooting the aliens before they can land. The aliens march back and forth and drop down a row at one or both edges of the screen (option). There is a "mother ship" which controls the motion of all aliens. If you knock out the mother ship, you stop the motion of the aliens. However, aliens continue to drop bombs until completely destroyed. You win the game by destroying all aliens and the mother ship. Your laser cannon will knock out individual aliens, the bombs they drop, as well as the mother ship. Optionally, the mother ship moves back and forth in a random fashion. Optionally, the mother ship (as well as individual aliens) may have multiple "lives". Optionally, the laser cannon may have multiple lives. Initially, there are "bunkers" between the laser cannon and the aliens, and which shield the laser cannon from alien bombs. However, both the aliens' bombs and the laser cannon's laser shots damage the shields and after four hits on an individual shield, it is destroyed and no longer protects the laser cannon. If any single alien reaches the ground, the game is over and the world, as we know it, is destroyed. GOOD LUCK!

Basic Requirements (100 points)

 * laser cannon: cursor controlled; launches laser shots.
 * laser: destroys aliens, alien bombs, and the mother ship, and damages/destroys bunkers; does not get stuck on top of screen.
 * bunker: takes 4 hits to destroy; animates with each hit (looks more and more destroyed; i.e., multiple depictions).
 * alien: under mother ship control, moves left and right >= 2 spaces; descends after some time; drop bombs; when reaching ground: game over and world is lost!
 * bomb: damages/destroys bunker; destroys laser cannon.

Extra Requirements (up to 50 points)

 * game won detection: all aliens and mother ship destroyed game won.
 * game lost detection: laser canon destroyed.
 * more sophisticated alien lateral movement; e.g., "edge" detection, so that aliens always travel to the extreme edge of the worksheet, even if side columns of aliens are destroyed; i.e., no edge "hiding" ability for laser cannon.
 * score counter: on screen binary or decimal counter; counts each destroyed alien.
 * bunker animation: different when hit from above or below.
 * animations: e.g., exploding cannon, exploding alien, exploding mother ship.
 * mother ship random movement.
 * image background.
 * multiple levels.
 * multiple lives for laser cannon.
 * multiple lives for mother ship.
 * multiple lives for individual aliens.
 * others ideas: describe