At the moment, Intel and ARM are usually Little-endian (although ARM chips can be put into either mode by hardware or BIOS at power-up). So it may be reasonably safe these days to assume that it's least significant byte first.
Be aware, though, that Cray T3E processors can only run in Big-endian mode, and customers at the National Ignition Facility in California may be a bit upset if they test your shoot-em-up and send 500 trillion watts of energy down the local sewers.
I haven't looked at documents for the latest AppGameKit, but, surely, if you can send bytes the receiver can sort this out?
-- Jim DO IT FASTER, EASIER AND BETTER WITH AppGameKit FOR PASCAL