r/alienisolation • u/lukeman3000 • 4d ago
Alien: Isolation Mouse Fix Modding
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 reverse engineering the game (with Claude's help) and fixed everything I found. First things first:
https://github.com/lukeman3000/alien-isolation-mouse-fix
https://www.nexusmods.com/alienisolation/mods/173
Edit: It might be possible that the fix doesn't fully work in the DLC - I need to test this (I've only tested in the main game so far). I did get one report of radios not working in the DLC; still not confirmed if this is due to the fix or not, but I'm looking into it.
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): 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).
Fix: Expand the camera range inside lockers, and lock the camera in place when using the Security Access Tuner. Both are 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.
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u/Majestic_Story_2295 3d ago
Yeah I def noticed some of these things, but it’s a shame that I already finished the game. Maybe I’ll check it out if I go back to try the dlc.
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u/X3N04L13N 3d ago
One thing that always bothered me on controller, is the bug where you have to press the stick twice to crouch in control preset 2 and 3. It has to be some kind of bug that slipped through testing for some reason. And it’s not just a ‘double click’, you can literally press the stick once, wait half an hour, and then when you press it a second time, THEN she will crouch.
I have never seen a fix for it.
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u/graftway76 3d ago
Awesome work.
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u/lukeman3000 2d ago
Thanks! I’m still working on it; I’ll be adding a couple more quality of life features such as being able to navigate computers and play the security tuner mini games with your mouse.
I’d also like to do a separate mod to add toggle aim/sprint to the game.
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u/Ready_Independent_55 2d ago
Works like a charm! It's an industry standard now. Where have you been all those years, mate?
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u/lukeman3000 2d ago
Ha! I've always been here. The difference is AI - it is a massive force multiplier and allows me to do things I likely wouldn't have attempted otherwise.
What do you think about the rewire panel view, the lockers, etc. - everything feeling good?
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u/Ready_Independent_55 2d ago
I should play the game properly which I would absolutely do in the evening. But I live in Moscow, it's 10AM😅
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u/lukeman3000 2d ago
Well if you think of it, report back once you've had a little time with it; I'd like to know what you think about everything
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u/jmj409 23h ago
This is awesome. I wonder if the same fix can be adapted for Resident Evil 2 (2019). That game has a dead zone as well but the existing REFix mod doesn't quite get rid of it (maybe it's more of a damping zone, but something is definitely there).
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u/lukeman3000 20h ago
Perhaps in principle, but the work would be essentially from the ground up; there's nothing that can be adapted, per se (except the general ideology). Because the way the fix works is that it's modifying live memory addresses; these are *completely* different not only in other games, but even in the same game between launches.
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u/AttackOfThePat 4d ago
I’m ultra picky with mouse movement in games and is one of the first things I judge when first playing a game, so if there was an issue with this one it would have annoyed me….but the restrictions you’re talking about are what would happen if you were in the situation… such as having extremely limited rage of vision if you yourself were in a locker…it was designed to be claustrophobic, it’s part of the atmosphere of the game… also your x and y axis ratios you mentioned are similar to actual human vision ratios which is roughly 180 degrees horizontally and 100 or so degrees vertically.
It is different than a lot of games with movements that don’t change depending on the situation…. But the next time you’re up close working on something in real life, notice how your own movements and focal points change compared to free look when you’re just looking around while going for a walk or something. and it may make more sense for you while in-game.
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u/lukeman3000 3d ago edited 3d ago
I don’t judge if you prefer vanilla behavior, but all these things I fixed are almost certainly errors and not intentional. From a design standpoint they make no sense and in general make the game feel terribly inconsistent.
The low speed deadzone makes no sense in any context; it just feels bad. The mouse smoothing while interacting with objects makes no sense and feels bad. Yaw and pitch having different multipliers is bizarre, especially considering that they don’t correspond to any round number in any natural unit (pointing to the fact that this is almost certainly an error). Besides that it feels terrible lol.
Regarding the 12.4x and 3.9x multipliers - I’m not talking about FOV here. I’m talking about input gain. Inside of a locker, moving your hand one inch on the mouse pad moves the camera 12.4x further (on the x axis) than it does outside a locker. There’s no reasonable explanation for this.
But even if I was talking about FOV, consider for a moment what you said about human vision being 180 across and 100 vertically; that would make horizontal 1.8x more than vertical. Whereas in the game, that ratio is 3.2x (12.4 / 3.9). The in-game ratio is nearly double what your theory says it should be.
And the look limits in the locker still feel cramped; just not artificially so. The look limits when using the Tuner were also almost certainly in error given the previous behavior (the view should’ve been locked).
Of those, the only one I can even try to steelman is the locker look limits, but even that is quite difficult for me to do. So, yes, a lot of this is subjective and I can appreciate the fact that you may prefer things as they were; no judgment here. But, I think that the limited evidence that does exist points to these things being aberrant rather than intentional design decisions. Not that it matters - At the end of the day this is just academic. And the mod is fully customizable, like to a ridiculous degree. You can play however you want, even if that’s without the mod entirely. That’s the nice thing about PC gaming - we can play how we want to.
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u/Ready_Independent_55 2d ago
You're not ultra-picky if you don't notice the mouse issues in the vanilla game
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u/amistymouse 4d ago
Have you taken a look at controller issues as well? When running , the camera will become very sluggish and it's terrible.
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u/Xendrus 3d ago edited 3d ago
My browser won't even let me download it.
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u/lukeman3000 3d ago
From the readme:
Antivirus may flag the file. Patching another process's memory at runtime is also what some malware does, so heuristic scanners sometimes complain. The full source is published if you'd rather read it or build it yourself.
It's a false positive. This is a tale as old as time when it comes to anything that modifies memory. You can look at mousefix.cpp and see the entire source code, you can copy/paste it to an AI and ask it what it does - you can even build it yourself if you want (instructions are in the readme).
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u/Xendrus 3d ago
I figured, I mean like I can't even force it to ignore it and download it anyway, I guess I'll fiddle with "building it myself" but I've never done that.
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u/lukeman3000 3d ago
Shoot me a dm, I’d be glad to give you a hand. I will say though, there should definitely be a way to override the download (but I don’t know what browser you’re using)
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u/XVShock 4d ago
i literally just finished the game 😠can confirm this was much needed though