Yeah you find out roughly what engine the game uses and then you can speculate as to how it does its mouse handling.

If it's source like it will likely behave like x, if it's quake like it will likely behave like y, unreal like z, etc.

Then you can use sites like

http://www.funender.com/quake/mouse/index.html

To do some of the calculations.

Even so, some of it is trial and error because even if you have the same sens, it may not be suitable for a different game.

It's also rather strange to want to match your desktop sensitivity which is a 2d thing with a cursor, to a 3d view frustum. You're kidding yourself if you think they will be perceived as the same in your brain and therefore evoke similar muscle memory.

I just want it to be similar in a way so that it doesn't feel completely different when I go in game. I use to have my desktop sensitivity really high and when I got back on quake it would feel like my sensitivity became much slower and I'd have to adjust again. I changed my windows pointer speed to something lower now something closer to my actual sensitivity in game and there is less of an adjustment period when you first get back on. MarkC &h8m3 posted a formula on how to do it a while ago but when I asked the guy that made that site, he said that their calculation was wrong & was 50% off in their speed.

Exactly 50 % off? Lower or higher? If you know that then just divide by 0.5 and add or subtract result ; )

You are exactly right we need to make our desktop 3d and based of the quake live engine. Then we can flick shot to the quake live icon or practice lg on our moving wallpaper. Alternatively we can have a counter-strike theme.

I can't wait to hear about all of the through-clicks and horrible click detection. <3

+'d buddy

and shortcuts warping

This guy actually tests out the sens for every game, even if they have the same engine. I left a message on his site once and he explained that's why some games with the same engine aren't all up there. I'm not totally sure what process he uses to find these, I think he analyzes pixel distance from video/screenshots after using a mouse macro. His sensitivity conversions are good though, I use the site a lot.
edit: found this http://www.mouse-sensitivity.com/forum/topic/...ion/?p=906

But to add to what you're getting at with the 2d thing, here's something I wrote in another thread:

Even if you ignore the fact that aiming is largely playing angles in a 3d space to your advantage and assume you are incapable of moving, FPS games are an entirely different control scheme because the player pivots from one point rather than moving a cursor across 2d coordinates. You can only match sensitivity between in game and windows at one specific vertical angle because aim sensitivity is based on degrees instead of screen space. Go into an FPS game and move your mouse a few inches to the side, then repeat the same movement after looking up - your crosshair covers a different amount of horizontal screen space because it is instead moving the same amount of horizontal degrees. Not only that, but your crosshair won't even move across what is horizontally aligned to it on your monitor if you're looking at a steep enough angle. Now realize that 99% of aiming mouse movements in FPS games involve not only a vertical element, but a changing one.

I might give the guy some $ anyway since it's a cool site.

just do a desktop with-cm measure x1.5 for 360/cm ingame. It works pretty well for 4:3 at least. It's then not fov dependent, and most games with fov 85-110 it works very well imo, feel on desktop/menu seems right after a long gaming session, not too slow or fast depending on what sens you use now.

in windows i have 6/11 800 dpi on 1680x1050, same resolution in cs go. what sensivity do i have to set in game to have the same as on desktop ?