RUR-PLE is a Python desktop implementation of Pattis's "Karel the robot". I started this project in 2004 and learned much while working on it, incorporating suggestions from teachers.
It is now obsolete.
Reeborg's World (live on http://reeborg.ca/reeborg.html, repository at https://github.com/aroberge/reeborg, documentation link to be found at http://reeborg.ca) is a much improved version.