Not just to you but to other comments too on the 'is_a?' issue:

The basic issue is that this is supposed to be a 'learn ruby' tool but rather than use the ruby class system (a fundamental thing to learn for beginners) to define what is in a Place they have used a custom non-class-based system instead. The result of this is that rather than allowing the user to choose their own way to do things (remembering that ruby is a 'there is more than one way to do things' language), it prescribes certain ways of working (or at least makes them easier than others).

I'm not saying everyone should program the way I do but I want to write a simple 'case warrior.feel; when Enemy;x; when Stairs;y; when Empty...' statement which is usually pretty clear and logical ruby but is prevented by this structure.