There is a ASUS CrossLink Cable. I am not trying to advertise ASUS, it just I happed to find it.
I thought that since You can perform transfer between 2 computers it might be possible to use it to play games. I do not know details of this process (whether data can go both sides at the same time) or if it is even possible to do it.
And if it is not possible directly I thought about possible solution. You would create file on both computers and each would be writing data into the other file. But there might be problems with synchronisation.
So, is it posssible to somehow communicate between 2 computers via usb cross-link?