How to make a bounding box with the A5??? My problem is that I can jump through the ceiling. And that isn't good for a shooter!^^ So who can help me?

There is a bounding box with A5 by default. You can scale it with min_x max_x (y,z). But the box only works with move_entity, trace and rotate commands.

or set a second hollowed cube, below the celing and set it to invisible on the groups menu which could be used for the boundary detection.

OK, But how would it look in a script?