How do I programming a game SDK direct to pins on an arduino?
Do I need to make my own bootloader ?
What SDK?
And by SDK do you mean software development kit?
No bootloader is needed to access the pins directly, quite an unrelated tool, it simply writes a sketch to flash at boot time if one is waiting to be uploaded.
X-Plane 10 SDK. How to do so the pins on arduino board recognize the X-Plane SDK? Do I need to programming header file or something like ?
I guess you have no idea what you are doing???
XPlane does not run on Arduino, it will communicate with devices using some protocol like RS232 over serial, maybe ethernet too.
You will have to write an interpreter to parse the commands coming in and then you will have to decide what to do with the command.