We recently had the opportunity to get out of the house with some new friends. They took us to Jumpinn in Heidelberg.
http://www.jumpinn.de/t3/index.php?id=107&L=1
The place is pretty big and there are a ton of climbing things and some trampolines inside.
Here is a list of the things inside along with a few pictures:
http://www.jumpinn.de/t3/index.php?id=35&L=1
There is a cafe type thing in there as well, but I'm not sure all what is on the menu besides coffee.
There is also another Jumpinn in Ladenburg, which is between Mannheim and Heidelberg (closer to Mannheim it looks). We have not been there yet, but here is the link.
http://www.jumpinn.de/t3/index.php?id=231&L=1