If you haven't yet, try reducing the mouse sensitivity in the GUI or by using the - key. That may reduce the oversteering. As for the camera following mouse movement precisely, that's very hard to impossible, given that mouse movement is mapped to key presses. I've literally spent hours trying to find the best mouse controls, so I'm not sure that it can be improved further. As you said, we'd probably need a new engine with native mouse support to correct issues like these.

Anyways, thanks again. If you find any more bugs or issues, please let me know. If I don't hear anything soon, I'll make it the final v1.1 and upload it.

I think it's an issue with the way Lara accelerates when turning, unfortunately. It makes some sense for keyboard controls, where you're expected to tap repeatedly to make small adjustments, but feels odd with a mouse. High mouse sensitivity feels good for small turns but risks her oversteering in large ones (because I guess large mouse movement = longer button press, and so it takes a while to "release" the directional button and respond to steering in the other direction?). Low sensitivity reduces that risk but feels unresponsive for small turns.
You get used to it, though! I'm finding myself spun around much less after just a little practice. It mainly happens when I panic in combat now, I need to get into the habit of using the Roll :p

I messed around on the mansion obstacle course in TR2 this morning and shot some wolves in TR1, and didn't come across any bugs.

That's exactly what I fought with. It's just not practical to have a single sensitivity because either small adjustments or big adjustments won't feel right. For that reason, I implemented some crude mouse acceleration (which has been in every version already) based on how much the user moves the mouse. Obviously, it's not perfect, though, and may vary based on individual configurations (like resolution).

In looking at my scripting, I see that I have different mouse acceleration settings for the Windows and DOS versions of TR1. I'm curious: which are you using? I did most of my testing on the Windows version, so it's possible that the mouse acceleration for the DOS version isn't quite as good as it could be.

I'm using the Windows version.

When you refer to oversteering, are you referring to too much steering for large movements or small ones. I've figured out how to prevent it for large movements, so that the steering stops when you stop moving the mouse, but that has the side effect of making quick flicks of the mouse do very well, so it's hard to abruptly turn and do a 180, for example. I imagine that that's probably worse than it is now, so I haven't enabled it, but I could if you think it's worth it.

If you're referring to small movements when you say oversteering, I think that a change that I made has addressed that. Now, steering is more proportionate to how much you move the mouse. See if this is more to your liking than it was before.

Edit: Link removed because the final version has been uploaded here: https://community.pcgamingwiki.com/files/file/1237-tomb-raider-mouse-helper-for-tr1-5/

My problem is with large movements, yeah, like trying to make a quick 90-degree turn in a hallway or run in a large curve/circle in combat. When I move the mouse fast enough to make the movement feel quick and responsive to start, it tends to go on for too long and I run into a wall/get turned around. I'm still training myself to resist the temptation and just move the mouse slower. Small movements feel a bit sluggish/sticky, but precise enough.

I'm seeing a new bug in the new version you've uploaded: Jumping repeatedly causes Lara to go into an infinite cycle of drawing and holstering her guns. I've also managed to get her stuck jumping up and down, though I can't reliably replicate that one. When this happens it also breaks the pause menu -- it's impossible to return to the game by pressing ESC or to access the "passport" in order to exit by pressing down, so I have to Ctrl-Alt-Del out.

The new version maaay feel a little better? Not sure I would have noticed a difference if I didn't know about it. But I haven't played with it very much yet because of the above bug.

Sorry. I had to make a change because I noticed that the mappings weren't working in the DOS version and, obviously, I didn't encounter the bug in the Windows version. I discovered how to reliably replicate it, though: simply by holding down Space. A change that I just made seems to fix it.

Edit: Link removed because the final version has been uploaded here: https://community.pcgamingwiki.com/files/file/1237-tomb-raider-mouse-helper-for-tr1-5/

Thank you, that was quick! :) It's bedtime here, but I'll play around with it some more tomorrow!

Hm, I'm still getting the gun cycling/stuck menu bug. On my first try I managed to climb around the mansion tutorial map for quite a while and it only hit once I loaded a savegame where I actually have access to guns, but on my second attempt the pause menu broke in the mansion as well.

Sorry. I remember it not triggering in my brief test, but I didn't test it extensively enough because I rushed to get it to you.

I believe that it's really fixed now... for the Windows version. It still happens in the DOS version, but I don't think that there's anything that I can do about that because I've had this issue before with DOSBox. I'll just add a warning that users playing the DOS version should probably not enable the Space mapping and should set Jump to Space in the game, instead.

Edit: Link removed because the final version has been uploaded here: https://community.pcgamingwiki.com/files/file/1237-tomb-raider-mouse-helper-for-tr1-5/

No worries! And yes, that one seems to be fixed!

Turning the mouse sensitivity down a notch or two lets me fairly reliably make those 90-degree turns. The problem with turning quickly still persists though, more specifically with changing direction while already turning. You can try it out by turning while running and then quickly moving the mouse left and right -- sometimes Lara will respond and change direction, sometimes she'll just keep running in a circle. The only reliable way to change direction seems to be to stop dead and then steer the other way.

Thanks for describing the issue. It took quite an overhaul, but I think that I've made the turning interruptable. Try this:

Edit: Link removed because the final version has been uploaded here: https://community.pcgamingwiki.com/files/file/1237-tomb-raider-mouse-helper-for-tr1-5/

You'll probably want to reset the sensitivity to the middle and then adjust it in the game to find a new comfortable setting. FYI, if you didn't know, - and + change the sensitivity in the game, there are 13 settings (corresponding to the 13 ticks on the GUI slider) and 7 is the middle mark, obviously. That's useful to know so that you know when you're at the min and max settings.

That's much better! Lara still has a bit of inertia when turning, like you'd expect, and responds reliably to changes in direction.

That's a big relief. It's never going to be perfect because it still just presses and holds virtual keys and, so, has all of the limitations of the game's keyboard controls, but, obviously, it needs to at least be predictable so that the user can get used to how it controls. Hopefully, it's predictable enough now.

I've just tweaked it a bit more. The main thing is that I removed the 1 pixel dead zone that I had. Before, Lara would keep running straight if you moved the mouse only a pixel to the left or right. That was to make it easier to run straight, because she would steer too much in either direction if you barely moved the mouse. I was able to reduce that, so I removed the dead zone and very subtle turns now feel more responsive.

Edit: Link removed because the final version has been uploaded here: https://community.pcgamingwiki.com/files/file/1237-tomb-raider-mouse-helper-for-tr1-5/

BTW, you wouldn't happen to have a gamepad, would you? I don't, but I can make the helper support gamepads if someone wants to help. See the thread that I posted in a few weeks ago if you can and would like to help with that:

https://www.gog.com/forum/tomb_raider_series/contoller_support/page1