I'm currently making 3d game with iocp based server. My question here is that is there any reason in making clients support iocp io? Because I think I only need one or two threads for io.
use iocp is one of way get notify when i/o request complete. your client can choose any way for this. this is absolute independent from way selected on server . client and server must use same protocol, crypto, etc. but not mandatory have common implementation details. client and server at all can run on different os. so your client not obliged to use iocp. but however using iocp the best way here