mechanics

mouse
  https://aim400kg.com/       - aiming game, might need to install/update flash
  https://osu.ppy.sh/home     - aiming game, abit complicated to install/play or atleast used to be

keyboard
  https://thetypingcat.com/   - typing game, speed typing/homerow, good for efficient finger coordination

eye coordination
  http://www.spotthedifference.com/    - great for dyslexics too, or have trouble reading