Windows isn’t quite like Linux in that typically apps don’t make syscalls directly. Maybe you could say what’s in ntdll is the system call contract, but in practice you call the subsystem specific API, typically the Win32 API, which is huge compared to the Linux syscall list because it includes all sorts of things like UI, COM (!), etc.

The project has some of the properties discussed above such as not having a typical main() (or winmain), because there’s no CRT to call it.