TTDPatch version 2.0.1 alpha 23 or later
Configuration file: gamespeed on|off|<speed>
Command line: -Yg
This switch lets you change the speed of the game ingame, ranging from one-eighth of normal speed to as fast as your computer can run the simulation. It uses the MoreHotkeys mechanism to change the speed, so that switch must be enabled as well. Since TTDPatch 2.0.1 alpha 49, it takes an optional parameter <speed> that controls the initial setting, from -3 (slowest) to +3 (fastest).
By default you can use the "Q" key to slow the game down by a factor 2, the "E" key to speed up the game by a factor 2 and the "Q" key to reset the game to normal speed.
If you have a ttdpttxt.txt file from an older version of TTDPatch, you have to change the "hotkeylistwin" line. Change the characters between the "x" and the "!" to be "qwe", for example change this:
After this, run mkpttxt.exe again.
This feature was contributed by Sander van Schouwenburg.