According to Steam forum posts the mouse acceleration can by turned off in the ini if you make the ini read-only before starting the game. Holding off on buying it until there are more fixes available, so can't verify myself.
Topic on Talk:Mass Effect Legendary Edition
That didn't work for me. Setting mouse dampening to false in the INI still had negative mouse acceleration applied. And it was never re-enabled so setting it to read-only shouldn't matter.
The dampening in ME1LE seems to be hardcoded similar to the original, as the ini tweaks have no effect on it at all (either inside coalesced_INT.bin or in GamerSettings.ini). It seems likely the first game will need a dll injection like the original did.
Should note that the dll fix for the original does not work in ME1LE contrary to some user reports on steam and elsewhere, and the ini fix currently displayed on this PCGW page or in fixes posted on NexusMods most definitely do not work in the first game.
From reports it seems the dampening setting does work in the other two games, similar to the originals. I've only played the first game so far in LE so can't confirm those.
Yes, the DLL fix didn't work for me either. Luckily it's not *too* bad, still playable. Considering the other games have options in the menu that actually work, it makes me wonder if it was something that would take too much time for Bioware to do. Especially since the PC ports of the games have been overlooked in general.
Yea it doesn't work, and the page currently both says it doesn't work in the input section, and says you can edit the ini to fix it in a separate unlinked section. Page is locked for editing and when I go to make an account, it's glitched and never sends me the email so yea can't edit it. Someone clean that up to at least be one or the other.
So I've been playing through the games and my experience has been that even setting the mouse dampening to false in the gamersettings.ini did not remove some form of acceleration that seemed to persist after this edit (the mouse aiming would wildly change speed in certain areas and might be based on framerate but I'm just speculating).
What I found that did work (although there might still be some kind of minor acceleration going on that doesn't bother me, but suffice to say it's "good enough") was using one of the many coalesced editors you can find to change both "bEnableMouseSmoothing" and "bUseMouseDampening" to false, which you'll find in the "BIOInput" section of the coalesced file.
This worked for all 3 games. I can't say whether you only need to change one or both of these as I didn't test beyond this once I found that my issue was resolved.
This can also be done for Mass Effect 1 and made mouse aiming reasonable. The programs I used to edit the files were LECoal for Mass Effect 1 and 2 (bit awkward to use as it requires using powershell commands) and ME3Coalesced for Mass Effect 3 (much more user friendly).
There may be better programs but those were the first two I came across that served the purpose I needed. It could also be the case that the "bEnableMouseSmoothing" can be disabled in the gamersettings.ini and resolve it that way as well but I never bothered to try.
AFAIK none of those fixes work for ME1, or at least they didn't for me. ME2 and ME3 already has mouse acceleration fully disableable in the options.
The coalesced edit I use for ME1 definitely improved mouse aiming to a more reasonable level but it may also be the case that there was some other mouse aiming issue that only affects certain systems because just turning off mouse dampening in the gamersettings.ini did nothing for me for both ME2 and 3.
This was a very specific wild jump in mouse aim speed that occurred in all 3 games but I couldn't say what the definitive cause of it was. I just know that my edits in the coalesced fixed it.
Changing the settings in-game in ME2 and ME3 disabled mouse acceleration for me. If you think your fix for ME1 works, then feel free to add it to a fixbox. I'm sure you will get feedback on whether it works for other people very soon.