Much appreciated pal, and to think this game very nearly never seen the light of day.
Scoring was a bit of a problem, originally you could knock up ridiculous scores by shooting stuff and not actually progressing very far, thats why I went for 1000 points per completed level.
I tried the time bonus arrangement but it wouldnt fit in the limited space available for that routine.
Not entirely sure what the ZTG is but I might include it in future releases.
Cheers,
Davey.