Haven't managed to beat this game in decades. Got the demo on a floppy as a child and tbh I didn't notice that it was only a demo until years later when I reached the end of the demo. But regardless of how often I come back to this game I still haven't managed to beat it (or get past the 2nd level). Also there is not really a point in playing within the 5 or 7 lives mode as it will prevent you from being able to play the final levels. So you've to grind it within the 3 lives mode all the way through.