In the Temple of a Thousand Doors, there is a pathway lined with trapezoidal pillars. It is possible, if you time your jump correctly, to jump on top of any of them. The second from the last on the left-hand side (if you're facing away from the center of the temple) has "zlep was here" written on the top. The credits list zlep as one of the programmers, and give him/her sole credit for scripting.