You can download HEAG Mobilo official app. In "Karte" menu you can overlay the whole network on Google maps. Other available maps that I know are mostly simplified versions that are not precisely scaled to their locations.
Bin grade noch nicht ganz sicher ob ich in Darmstadt studieren werd (die ganze Scheiss-Geschichte gibt's hier). Aber wenn, dann wäre das schon eine Idee.
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Kann sie ruhig mal PMen.
Are you searching for a commute? Or do you want to take a detour to drive in nature? Should that be the case, I can only recommend driving the R8 for most of the way.
My App reccomendation is Öffi, if you have an android:
https://play.google.com/store/apps/details?id=de.schildbach.oeffi
It works a lot better than the official apps by DB or RMV.