Difference in Physics panel?

Hi,

I have a model to which I want to apply physics settings on the meshes.
I want to get this panel to apply ‘rigid body’ settings:

But I get this panel in the file that I’m working on:
http://i.imgur.com/b1qSg.png

The blender version is exactly the same in the 2 images (2.58.0). What could be different in the 2 files? And how can I access the Physics panel from the first image?

Greetings,
Xochipilli

You only have to select this here


Thanks,
And I kept thinking that I need to switch the Screen lay-out, two buttons to the left, to ‘Blender Game’.
I feel so stupid now that I didn’t notice that button. =(