These small robots walk downhill by balancing from one foot to the other. 
They are not motor powered and rely solely on gravity to maintain their  balance while walking.
As simple as they appear, these walkers require one week of design. 

I believe it' s the first LEGO dynamic walker ever made, I presented it at LEGORLD 2004 (biggest European LEGO exhibition).
I was inspired by MIT dynamic walkers.

chrismaker@noos.fr