Please,read the C-Script tutorials for beginners and post questions like this in the Starting with game studio section
Code:

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 my.skill5 = 15; // max tilt
 my.skill6 = 0; // min tilt
 while(1)
 {
  while(my.tilt < my.skill5)
  {
   my.tilt += 2 * time; // speed
   wait(1);
  }
  while(my.tilt > my.skill6)
  {
   my.tilt -= 2 * time;
   wait(1);
  }
  wait(1);
 }

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