Changes
/* Keyboard clash */
The problem is much bigger in 2 player games.
It is possible to avoid or minimise the problem by carefully choosing the controls. The problem also occurs when using digital joysticks because these are part of the keyboard matrix.
If you visualize a rectangle in the keyboard matrix above, where 3 of the corners are 3 keys you have pressed. Then the key in the fourth corner will also be pressed this is the "ghost" key.
On Plus it is possible to avoid it mostly by having one player on analogue joystick and the other on keyboard/digital joystick.
== One line scanning routine ==
