Go here and download this:
https://github.com/sndrec/MouseThingy/releases/tag/1.1
Also, make sure you limit the fps to 60 to have better aiming fluidity. Don't listen to those people above, they have nothing useful worth digesting.
"Controls are similar to other 90's shooter games" - What fps games are you referring to? H2V is unplayable for a M/K user without bypassing that underlying abomination it came with.