As i said, inspired. There are several points taken from the TV serie starting by the time rift out of an incident at a nuclear plant, to the accidental time travel that mess with someone's early family (ok, this one is also Back to Future), the mysterious scarfaced guy from the future that moves the strings from behind, the elderly weird lady that seems to know a lot and who says nothing and so on.
Then of course it's also a mostly light hearted porn game about banging girls in 2 different time periods.
And, by the way, i don't know if it's openly stated but it sure widely agreed that this game took inspiration from Dark.