Move with the arrow or ASWD keys, fire with Z or M keys, pause with SPACE. You can also pause by just moving the mouse outside of the game window.
Collect refugees who wave at you from the ground, fly over the runway in front of the tower where they'll drop off and run home. Look out for the abductor UFO's which try to kidnap the refugees and transform them into cyborgs who will relentlessly track you down and harass you with photon bullets. If you can catch a refugee dropped from an exploding abductor before he hits the ground you'll get some bonus points just for having style.
Exploding enemy ships eject bonuses of various kinds: +nbsp;alien crew = 50 points +nbsp;silver stars = 100 points +nbsp;gold stars = 500 points +nbsp;white crystals = score multiplier +nbsp;blue crystals = shield +nbsp;purple crystals = rapid fire +nbsp;red crystals = extra life You can ram or shoot the alien crew, all the other bonuses have to be collected. There are 2 levels of rapid fire - if you collect a second one before the first has run out you'll have very rapid fire indeed. Your ship is equipped with a tractor field so you only have to get close to a bonus and it will be sucked in towards you.