The default user interface is 2-dimensional, consisting of 2 windows side-by-side (split screen). One window is always an overhead view, and the other window is split into 2 windows, one on top of the other: left-side/right-side, or front/rear. All 3 windows are separated by splitters, so it's easy to resize them. Clicking on the point of intersection in the center of the screen resets the sizes of the 3 windows to their default values.
User Commands
The user uses the cursor keys to go forward (up arrow), left, right, or backwards (down arrow). Ctrl+Left Arrow and Ctrl+Right Arrow rotates the overhead view 90 degrees in the given direction. Clicking on an object carries out the default primary user action, and right-clicking on an object brings up a popup menu of choices. Pressing Tab highlights the next command in an onscreen menu. Clicking in the non-overhead view toggles between left/right and front/rear. Right-clicking in the non-overhead view and selecting Backpack (or typing Ctrl+B) displays contents of backpack in the window clicked upon.