Is your game based on something else? I have a vague recollection of a very early PC game that had swirling mists and you had to make pretty basic choices like which direction to go out of a room.
On the cross-over cable topic, I have read that Macs are smart enough to take care of this internally but perhaps no such luck with PCs...I do have something I think is a crossover and it didn't seem to work either but I will try again.
I did discover that with ICS, it appears that the Ethernet port gets assigned a fixed static IP address. I will have to change the Arduino code to reflect that and see if it works.