Okay so since it seems to be rush hour here, I'll add new hints now for these;
#9: The final game in this franchise that included a number in its name.
Hint 2: At least this time it's just the actual number and not one with a few zeroes added to it.
Hint 3: This was also the last game in the series which the developer had full control over, because they were bought by a certain publisher (who did already publish this game though), and it shows. It really shows, because the sequels are an insult to the first four games.
#8: Halfway through one part right after you jump you can turn right and visit a location from another game.
Hint 2: And it's a nice looking castle.