Crush the Eggs is a drawing puzzle: eggs sit on platforms and you draw a shape that becomes a solid object, falls under gravity, and has to smash them. Where you draw and how heavy the shape is decides whether it works.
Later levels put the eggs behind obstacles, so the answer becomes a lever, a ramp or a domino rather than a weight dropped straight down.
Whatever you draw becomes a solid physical object with mass, which then falls and interacts with the level — so shape and placement both matter.
Usually because it's too light. Compact, filled-in shapes have more mass than long thin lines, and dropping from higher adds speed.
Yes — draw with a finger. Nothing to install.