Windosill is a puzzle game that involves a cute toy car. Players need to guide it through different, single screen rooms and discover the solution to open up the next room. This is always done by locating a cube that unlocks the door. In order to do so, items in the environment can be dragged and clicked. By interpreting the results, the actions can be linked to find a solution. The toy car itself can also be picked up and moved around, and interact with the objects in a physics-based environment.

Many objects and themes in the game also appear in earlier Vectorpark games, with an often absurdist style. Although most rooms seem simple at first, they require a lot of trial and error to discover the solution. The first levels can be played free of charge in a browser. The full game can be downloaded for a fee.

The later-released iPad version adds a sketchbook gallery, a level selection, and a translucent mode that allows the player to see how levels have been put together with 3d polygons.