One of the main elements in LIMBO. The nameless boy can suffer death from gravity, if he falls from a certain height (and this height can vary from one puzzle to another: at places he can survive a quite big fall, and at others he dies from a relatively small fall). Besides of having an incredible valueable influence on the game physics, later in the game, a number of puzzles is specially centered about gravity, as it involves gravity manipulation.
Pushing a normal gravity switch will chance the gravity to where ever the switch's arrow points. Once triggered, another switch has to be used, in order to adjust the gravity.
Works similiar to normal gravity switches, except they have a timer inbuilt, which will count down, whenever the device is triggered. Once the timer runs out, the switch will change the gravity to, what it was before the switch was pressed. Some time switches can also be pressed by pushing a crate unto it or standing on it. At a point near the end of the game, the player is forced to press a gravity time switch, which seems to break the switch, changing gravity up and down, each time the timer runs out.