Probably, though that involves a little bit of retroactive attribution: at the time it was just an online game on some network. In 1980, ARPANet, PLATO, and other large multi-site networks were roughly peers. ARPANet turned out to be the one that "won" and evolved into the Internet, the global internetworked system that everything else got rolled into. But I'm not sure that retroactively changes the status of what a game in 1980 was: if one game was on ARPANet and one was one PLATO, you couldn't really say one was one "the internet" and the other wasn't, without being pretty anachronistic.