Since version 2.5, Clickteam Fusion 2.5 comes with a full implementation of the well-known Box2D engine. Box2D is a cross-platform physical engine. It simulates the movements and behaviors of objects as if they were in the real world, taking the mass, density, gravity etc. into account when doing its calculations. The result is an amazing and really accurate movement of the objects : they do look as if they were in the real world. Clickteam Fusion 2.5 implementation of the engine is made to make things simple for you. No complicated vectors or force. You just choose a movement in the list of Physics movements, set its properties and that's all: your objects behave as they would in the real world.