haha, connect the same kind of cable you would use for connecting to any kind of Macintosh printer (non usb era) to the printer port of each mac and they will network together automaticly. (provideing hte AppleTalk and File Shareing software is setup)
the softwaqre presumeably works via AppleTalk networks so any computer that it works on through and kind of appletalk connection (the AppleTalk software facilitates data transmission via LAN or modem so the program talks to the AppleTalk program then appletalk interprits how to convey the data) so connecting the two computers via a regular Mac Serial cable and then activateing file shareing then go to the chooser and select AppleShare (witch yes System6 can deal with AppleShare so long as you have compadible versions, a compadible for System6 version can be found bundled with System 7.1 and System8.0-9.2.2 on the CDROMS or for 7.1 on either the Install 2 disk or the tidbits disk i dont remember witch)
if you select AppleShare form the chooser on either mac and see the name of the other computer apear in the list then the computers are networked fully and you should be able to run the game.