Hi,
apart from the recent "zigzag" mode there is now a "paraxial" mode in pen tool. In this mode, the user can only create straight line segments that are parallel to one of the coordinate axes. Normally, each line segment is drawn perpendicular to the previous one. The direction of the line segment being drawn can be toggled with Shift. When clicking on the start anchor, the path is closed with an L-shaped segment (the direction of which can also be flipped with Shift).
Let me know if you have any issues with it. [1]
Max
[1] Known bugs: When creating the initial segment with Shift, the second segment is parallel to the first one instead of perpendicular to it (although all subsequent ones get drawn correctly). Moreover, when closing a path the final segment is sometimes drawn slightly slanted.