FreeBASIC is a great descendent of QB, which is suitable for serious, even commercial projects. It has seperate "qb", "fb" and "fblite" dialects. "qb" is very highly compatible with QuickBASIC, while "fb" (the default) is a modern language which has almost all the features of C++98 except multiple inheritance and templates.
I'm co-maintainer of a large RPG creation engine written in FB.
I'm co-maintainer of a large RPG creation engine written in FB.