Chess, a PD game in Basic by ???
– probably some more games… (I have also seen an advert from GCP in Analog or Antic, that listed the following games: The City, Cybertank, Cybership, Bio-War, Lords of Space; I am not sure if they are all available for the Atari, A.M.) To play these games online, one would not only require an Atari computer, but also a modem, a modem-driver and/or a terminal program (like Kermit, Bobterm, Teleterm, A-Term, Ice-T, BBS Express Pro, etc.). See also the sections 7.8, 10.1 and 10.2 which tell you more about modem/terminal programs and modem hardware for the Atari…