Algodoo

Uses A to switch between states.
Press A continuously quickly to move in a
← Direction, Do not press A continuously quickly to move in a → Direction.

An example of toggling states using Mine and Danneh`s "3D" realtime collision layer switching via pressing of keys.

Although not a perfect creation, an example of what doing this kind of thing could create. I`ve noticed that it can be difficult to implement two keys at once, as it is very easy to accidentally put in an extra bracket somewhere, causing the entire process to break.