The Midttrafik Live app can show you where the busses in Aarhus are, and how delayed they are.
MobilePay is the payment app of choice for most smaller businesses. I think it requires a danish bank account though.
If you plan on taking public transit a lot, get a Rejsekort.
For TTRPGs in and around Aarhus take a look at https://www.facebook.com/groups/aarhusrollespilshygge/?ref=share
For boardgames in Aarhus take a look at https://www.facebook.com/Victorypointaarhus or https://spilcafeen.dk/