http://bugs.winehq.org/show_bug.cgi?id=29168
--- Comment #79 from Agifem agifem@free.fr 2012-01-05 08:52:23 CST --- It's not just an aknowledgment. It also sends a little over 1Kbyte of data. It's not the socket answering, it's the application talking back to the server.
I didn't have the time on the winedebug trace, so I hadn't noticed the status 0 call was happening so late. Now that I think about it, there's nothing suggesting it's a socket anomaly. The WSARecv is called correctly, and responds correctly (it seems), then the game doesn't send more data.