You will no longer worry that you will be run over by super fast locomotive on a straight line.

ChangeLog

0.15.3 : I made correspondence of negative speed (2017-05-26)

0.15.2 : Added to "mild mode" in control.lua (2017-05-22)
The default setting is "normal mode"
(I'm recommending "normal mode")

0.15.1 : I tried to mitigate some execution (2017-05-19)