You probably could write a program that converts the DBPro syntax into C++/DarkGAME quite easily, as malcolm is doing for us.
However, solely depending on a converter is a very unwise thing to do, as it will not take the advantages of C++ in anyway. Maybe a little faster but the code is going to represent C more than C++. You have to remember, C++ has object-oriented features which are very useful especially in game programming. I would just rewrite the game altogether whilst looking/copying&pasting the converted code and adjust it to use the OOP features well.
That was probably unneeded but thats how I am D:
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