Algodoo

Although tidally locked to Jupiter (always facing it with the same side, like our moon) Io experience enormous tidal forces because of the eccentricity of it´s orbit. These forces raise the ground up to 100m and are the cause of geological acitivity that make Io the most vulcanicly active object in our solar system.
Pressing "i" you can observe the elliptical deformation of Io when getting closer to Jupiter during a revolution. (Of cource nothing is to scale or we wouldn´t see much of it)