Why the sensitivity of the mouse changes between vertical and orizontal movement? Is there a way to fix this?

yes. there is a variable for this, check the documentation in the docs folder.

Do you mean the "doc" folder? Any idea which file should I check, specifically?

Sorry for the late response, I wasn't able to post yesterday night for some strange reason.

Anyway, I modified the value to 0.5 and it works fine, thanks for your help!

OK, I am a little dense here.

What file location do you open up to actually change the sensitivity value in?
I see a description of it as mentioned in the "new_config_vars.txt" file, but where do you actually make the change itself.

TX

You can find the setting in the file user[dot]bnd. Just open the file in Notepad and edit it, by default it has the line "mouse_sensitivity_y_scale 1" so just change the number to whatever you wish the y-axis factor to be.

edit: Having some problems posting the filename.. Hope you find it :P

Thanks, I will check it out when I get back on the game PC.