The object of this game is simple.
The enemies will fire at you. Evade their fire and return this fabulous weapon against them.
There are different types of enemies who fire different types of weapons. This will make it harder as you go along.
The game itself is played with the arrow keys. Additional controls are space for the start of the level, and mouse to buy health (requires a certain amount of score)
The enemies will fire. Every enemy can be destroyed before they fire, but that is not a requirement. Only ensure that there aren't too many enemies at the screen at a single time. For the rest, don't look at their position for your next attack. Know where they are but do not play games with them. Follow the firing as closely as you can and dodge that (enemies are harmless by itself so you can fly in them). Sometimes dodging the fires by changing the direction quickly (including opposite directions) might help you. Steer in circles, preferabely around the enemy. This tactic will evade most bullets but require a few reflex movements to avoid being shot at. Getting hit is not a problem. It will just drain a little bit from your health, and you can replenish that with enough score points.
Link: http://www.spele.nl/game/ontwijk_de_stukken/dodge_2.html