Red Pen is an fountain pen that has red ink on the tip of the pen. It is a object or specifically a tool you find in the game Killswitch.
~The Red Pen is a object you can find in the game KillSwitch.
~You can draw with it on the board in-game, and Ghast1989 was observed writing down 'ghast' onto the wall. The purpose behind this is unknown.
~If you get The Note and drag the red pen over it you can see a HELP message written in red, which is required to load up into the mail pipe to proceed.