The score is reduced during play, why?

Answer:

(Only in the unregistered version)

When the aeroplane with the �Register Now!� banner hits a bird the score is reduced by 10,000 points. This annoying little feature is only there to persuade you to register SinkSub Pro. The score loss will not bother you after registering this game. The aeroplane and the birds appear randomly on the screen. If you are lucky you can get away with only a few hits.