In case your not aware of it, there are some arranged kick abouts both at the Zoo on Saturdays (i think) and also at Saalsporthalle pitches on other days.
You can check
FootyList but it seems like not much is happening at the moment but I assume it will be running again soon.
They used to be every Tuesday and Thursday evening and sometimes on a Sunday and would get a lot of people playing. Things died off a bit last year, I hope it gets going again soon.