Press ~ (Below escape key) to open the dev console

Now enter this command

i_mouse_smooth 30

Hit enter to apply the command, now do the same with this command

i_mouse_accel 0

Now youre done, during your current play-session mouse accel will be disabled!

Alternatively you may place these commands in your system.cfg so they dont disappear when you load the game up next time.

To access the config go to your Steam folder/steamapps/common/crysis3 and in that directory your system.cfg file should be there. Paste these 2 commands there in their own lines each and save the file. Now you can start and play every time without issue!

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