SR-50 automation is a multiplayer cheat which causes Doom's StrafeRun-50 (SR-50) mode of straferunning to occur automatically. Wallrunning speeds may also be accelerated beyond that of a normally-executed wallrun. This is not to be confused with "normal" straferunning; SR-50 is a different type of straferunning that is normally very difficult to activate and control.
SR-50 automation is considered unfair, as it provides a means for the cheating player to use SR-50 at a level of effectiveness that is not humanly-executable and is fully automated, functioning without any input from the cheating player. The end result is a fully-automated straferun speed that is significantly higher than a non-cheating player can achieve.
Implementation of the cheat typically involves a modified mouse driver.
 Technical explanation
SR-50 itself is not a cheat; it is a normal characteristic of Doom movement. It is the automation of SR-50 which is a drastic cheat.
To understand how SR-50 works, it is necessary to first explain how Strafe-50 and normal strafe work (which are separate but related mechanisms to SR-50).
Doom has two ways in which strafing (stepping directly sideways) can be achieved. One can strafe either by defining separate left and right strafe keys, or by using a strafe-on button that can either be defined on the mouse or the keyboard, used in combination with a signal which normally turns the player.
Using these two variations of activating strafing, there are two different kinds of strafing.
- "Normal strafing" causes a sideways relative Doom speed of "40" and is achieved by either:
- Defining separate strafe keys, which offers the highest agility for player movement and is the configuration choice of most if not all skilled players, or,
- By holding down strafe-on while activating a key that turns the player.
- "Strafe-50" (also known as "faststrafing") is faster than normal strafing, causing a sideways relative Doom speed of "50". It is 25% faster than normal strafing, and is activated in one of two ways:
- By activating three key functions at the same time: strafe-on, one separately-defined strafe-left or strafe-right key, and a turn left or turn right key. The strafe-on key can either be defined on the keyboard or on the mouse. Or,
- It can be activated by holding down a strafe-on button (either on the mouse or the keyboard) and moving the mouse to either side at a rate of speed that will generate a full speed strafe.
It is important to note that while the strafe-on button is activated, both mouse movement from side to side and the normal left and right turn keys on the keyboard cease to be interpreted as a signal to turn the player, but instead are taken by Doom as a strafe command. This inability to immediately turn artificially limits the reaction time and maneuverability of a player (especially a player using a combination of mouse and keyboard) who is in Strafe-50 mode.
When Strafe-50 is combined with straferunning (a simultaneous forward or backward movement at full speed, which is a Doom speed of 50 as well), Doom creates the relative forward-angled speed of 50 from these two 50-speeds (one in each direction), and applies a diagonal-movement miscalculation to this number. The full speed of the player who is activating SR-50 is relative speed of 141%, and the player is turned at a 45 degree angle.
In order to make this happen without moving the mouse steadily across the mousepad (problematic to maintain simply for a straferun), one has to activate 4 functions at once: Strafe-On, a directional strafe defined with one key, a turn in one direction, and a forward or back.
This contrasts with "normal straferunning", in which Doom takes the simultaneous forward or backward movement from a straferun (a value of 50) and the "normal strafe" speed of 40 and combines them for a relative forward-angled speed of 45. When the known "straferun" miscalculation Doom has is applied to this number, the normal straferunning player comes through at a relative speed of 128%, and the player is turned at a 38 degree angle. All that is necessary to activate normal straferunning is a forward or backward key operated simultaneously with a directional strafe key.
Skilled Deathmatchers have historically not used SR-50 as their primary straferunning mechanism because of the intense difficulty in-game caused by the awkwardness of SR-50 activation and the inability to turn while in SR-50 mode. To turn, the player must first release the strafe-on control, and only then will turning of the player be possible. This requirement makes SR-50 unsuitable most of the time in Deathmatch, which typically requires split second reactions due to unanticipated appearances and movement of the opponent. Releasing the strafe-on button and then turning causes too slow a reaction time to the opponent's movement to be able to risk use of SR-50 frequently. Furthermore, when a player is in SR-50 mode and is running down a corridor, small adjustments in angle are difficult, limiting the player's ability to aim with the mouse aim. This limits its prospective uses in Deathmatch.
- This writeup incorporates text from StrafeRun-50 Automation cheat, used with permission.