Disabling Mouse Acceleration

Mouse acceleration increases the speed of your mouse cursor based on the speed you move your mouse. This might sound like a good idea but it causes problems - if you move your mouse from point A to point B then you'd expect your cursor to do the same thing each time you move the mouse between those two points; with acceleration enabled it won't because you'll vary the speed that you move the mouse between those two points and end up with inconsistent aiming.

Launch options

NOTE: Most of Source/GoldSrc games on Steam now have in-game settings which allow you to easily configure mouse acceleration. Use this method only if your version doesn't have this feature.

1. Right click the game in the Steam games list and select the properties item.
2. Click 'set launch options' under the general tab.
3. Paste the following into the window:

   "-noforcemparms"

4. Hit ok and you're done.

In-Game options

For Half-Life 1:

Enter the game's settings, under the Mouse tab check Raw Input and save your settings.

For Source Engine games:

Any Source game since SteamPipe should have a slider to configure Mouse Acceleration under the Mouse settings.

Mouse Acceleration can be disabled via the In-Game console:

m_customaccel 0

Third-party applications

Try one of these fixes if none of the above methods has worked for you.

RInput (recommended)

RInput is probably the best tool used to remove mouse acceleration from GoldSrc games. This tool does NOT remove mouse acceleration from your system.

Usage

Enter "hl.exe" before you launch the game. The program will execute upon the game's launch.

Get it here (113KB).

MarkC Mouse Acceleration Fix

NOTE: This fix will remove the mouse acceleration completely from your system, not just the game. Use wisely!

MarkC Mouse Acceleration Fix is a registry file that removes Windows 7, 8 or 8.1 mouse pointer acceleration.

Get it here!

Usage/Installation

1. Find the display DPI that you currently use:
   

   Click Start, click Control Panel, select Appearance and Personalization, select Display.
   

   See if you have 100% or 125% or 150% selected.
   

   (On Windows 8.1, if you see a 'Smaller...Larger' slider, then:
   

   the 1st slider position will be 100%,
   

   the 2nd slider position will be 125%,
   

   the 3rd slider position (might not be shown) will be 150%.)

2. Open the ZIP file that you've downloaded.
3. Select the folder that matches the Windows version you use and Double-click it.
4. Select the REG file that matches the DPI% you use and Double-click it.
5. Answer Yes, OK to the prompts that appear.
6. Reboot or Log off to apply the fix (you have to reboot or Log off).

To remove the fix, follow these steps:

1. Open the ZIP file you've downloaded earlier.
2. If you use Windows 7 or Vista or XP:
3. Select 'Windows_7+Vista+XP_Default.reg' and Double-click it.
4. If you use Windows 8 or Windows 8.1:
5. Select 'Windows_8.x_Default.reg' and Double-click it.
6. Answer Yes, OK to the prompts that appear.
7. Reboot or Log off.

Windows 8.1 mouse stuttering

In Windows 8.1 Microsoft has introduced a new way of handling mouse input, so games that don't have support for raw input ended up with very weird mouse movement with stuttering and whatnot. There's an official update to fix this issue.

1. Download the appropriate version of the update for your system from this page.

   If the update says that it is unapplicable to your system (and you're sure that you picked the correct one), it means that it was automatically installed by Windows Update.

2. Scroll down that page and follow the instructions for every game, in which the problems were present. Note that some games (most Source Engine games) are fixed by the update automatically, which means that you don't have to specify them in the registry.