First, run setup.exe.

Then:

Choose:

Mouse X Axis ( analog_turning )
Mouse Y Axis ( analog_moving )

It seems, you don’t need Y axis mouse moving, i.e. forward/backward. But actually, it’s needed for the analog reading of mouse movements. I don’t get the difference between “analog” and “digital”, in this case. I guess, “digital” uses a driver, while “analog” reads mouse signals directly from the port. Thus “analog” mouse controlling is more “fair”, i.e. the game decides how to interpret signals by itself, and makes moves smoother.

Don’t try other options, you need only analog_moving.

You can also tune mouse sensitivity on every axis here:

Mouse X Axis Scale
Mouse Y Axis Scale

Pay attention that values can be negative as well, and it means inverted direction of movement in the game.

Don’t forget to define any key to use for mouse aiming (“U” by default).

After that go to

You have

Mouse Aiming Mode:
(o) Mouse Aiming is a toggle button
( ) Mouse Aiming is a momentary button

-The first one means that the “U” button (or any other you have chosen) will switch moving mode from forward/backward to look_up/look_down. Press it once (“Mouse Aiming On” appears on the screen) and play Blood like CS or any other game with free look.

-The second one means you have to hold the “U” button (or any other you have chosen) to look up and down. Maybe you like to play this style.

You also have to invert aiming if you don’t wanna get “plane piloting” style of moving in the game.

(o) Invert Mouse Aiming up and down 

You can do the same thing by just changing mouse sensitivity to negative, as it was said earlier. But remember that in this case you also invert direction of Caleb’s moving forward/backward while mouse aiming is off.