In the scene in Kevin's bedroom, he's briefly playing a handheld game machine. It has been identified as Electronic Quarterback from 1978:
There's an in-browser emulator of it over in the Internet Archive, complete with manual, for anyone who wants to try it (I haven't tried it myself, since I don't know the rules of American Football, which I imagine is a requirement). Also, I found this amusing commercial for it, where it's compared to a competitor (kind of an predecessor to "Sega does what Nintendon't", "I'm a Mac and I'm a PC", etc.):
Actually, isn't there something a little Tron-esque about the commercial? Two anthropomorphized video games talking to each other?















