[Question] V15 clean source

Does v15 source can compile into vs 2012?

or does anyone know how can i convert v15 source vs2003 to vs2012

Of course you can compile the flyff source code in Visual Studio 2012 - it just takes some adjusments to it to compile it without error messages (and some more work to prevent from bugs and stuff).

There is a released source code for Visual Studio 2012 out there - just use the search function.