[Suicide Junkie]

There is a TCP/IP mode, yes.
However, as a Turn Based Strategy game, you don't need it.

There is no reason why players need to be online at the same time, other than the fact that you get through more turns if your schedules match.

When playing via Email/FTP or PBW, you take your turns whenever you like.
You can even play while the other people are sleeping or at work/school.