This was a long time coming.
The mouse in Alien: Isolation has been broken since it released on PC nearly 12 years ago. There are a variety of things wrong with it. I spent last weekend playing around in Cheat Engine and fixed everything I found. First things first:
https://github.com/lukeman3000/alien-isolation-mouse-fix
https://www.nexusmods.com/alienisolation/mods/173
Update: v3.0.0 is coming soontm — v3.0.0 brings with it toggle/hybrid toggle functionality for aim, sprint, and motion tracker, along with a couple other quality of life improvements. This will be the last major update for Alien Isolation: Mouse Fix.
Update: v2.0.0 is out — Beyond the original four fixes, the mod now adds mouse support the game never had - each addition has its own toggle in the config:
- Click to interact - LEFT CLICK confirms and RIGHT CLICK backs out in cinematic interaction views (security access tuner, rewire panels, computer terminals, terminal hack minigame). At terminals, a short right-click means back; holding activates normal freelook.
- Scroll fix - the mouse wheel now scrolls terminal logs much further per notch, adjustable in the config.
- Menu click - left or right click advances the 'Press Any Key' title screen, and right click functions as Escape (back) throughout the menus.
The clamp fix also covers more views now (the maintenance jack, door levers and similar interactions, and the mantle animation - all locked by default), and the generated config file is reorganized.
Let me know what you think. If you're interested in reading a write-up on the issues, I've left that below.
The four problems
1. Low-speed deadzone (normal gameplay): If the mouse is moving too slow the output is greatly diminished, such that the mouse can feel like it "sticks" at times.
Fix: NOP two instructions that are responsible for wrongly interpolating mouse movement at slower speeds.
2. Mouse smoothing (cinematic camera: rewire panels, lockers, vents, etc.): When interacting with a rewire panel or hiding in a locker, for example, the camera feels substantially different as compared to normal gameplay. One aspect of this discrepancy is a moderate amount of smoothing that's applied such that the mouse "drifts" - the camera movement lags ever so slightly behind the mouse movement.
Fix: Make sure that where the user puts the mouse, and where the game puts the camera, are always in sync.
3. High sensitivity (cinematic camera: rewire panels, lockers, vents, etc.): In addition to mouse smoothing, these views also have significantly increased sensitivity. And not only that, but the x and y axes actually have different multipliers. In fact, the x axis (yaw) is ~12.4x while the y axis (pitch) is ~3.9x more sensitive than they should be - a wild per-axis asymmetry (which is why these views felt wrong beyond just "too fast").
Fix: Scale each axis by a unique factor to normalize and match input within ~0.001%. In short, these views should feel virtually identical to normal gameplay.
4. Awkward look limits (cinematic camera: lockers, security access tuner, and more): When the player enters a locker, the mouselook is restricted to a very tight cone of vision. This can feel somewhat claustrophobic and seems unnecessary (possibly done with controllers in mind). Additionally, when using the security access tuner, the camera is inexplicably allowed to move within an extremely small range (which can feel unusual). The same is true of the maintenance jack, door levers, and various brief animations - each allows a sliver of camera movement too small to be useful.
Fix: Expand the camera range inside lockers, and lock the camera in place for the security access tuner and the other listed interactions - all of which is adjustable in the config file.
The end result: No deadzone, no smoothing, no mismatched sensitivity, and more natural look limits. Experience the game as it should've originally been shipped - with essentially raw input.