How the Physics Work: Building a Game with Matter.js

Every shot you take in Free Flick Football is governed by real 2D physics. There are no canned animations, no predetermined paths — the ball genuinely bounces off pins, walls, and goalposts according to the laws of Newtonian mechanics. This is what makes the game feel satisfying and what makes bank shots and trick shots possible.

Under the hood, the game uses Matter.js, an open-source 2D rigid body physics engine for JavaScript. Matter.js handles collision detection, force application, friction, and restitution (bounciness) for every object on the board.

The board is a top-down 2D surface with zero gravity — think of it as a perfectly flat table. The ball has friction (0.02) and air friction (0.012) that gradually slow it down after each shot. Pins have high restitution (0.9) so the ball bounces off them energetically, while the ball itself has a restitution of 0.7 — enough to bounce but not so much that it pinballs forever.

When you flick the ball, the game applies a force vector calculated from your drag angle and distance. The force magnitude is your drag distance multiplied by a constant (0.0008) up to a maximum power cap. This means the slingshot gesture directly maps to the physics impulse — drag further for more power, angle your drag to control direction.

Goals are detected using Matter.js collision events. The goals are static bodies positioned at each end of the board. When the ball collides with a goal body, the game registers a score. The goal areas have depth, so the ball visually enters the net before the score triggers.

One of the trickier engineering challenges was making sure the ball never tunnels through walls. At high speeds, a physics engine can miss collisions if the ball moves further than a wall's thickness in a single timestep. The solution: the physics walls are 80 pixels thick (much thicker than the 12-pixel visual walls), creating a generous collision zone that catches even the fastest shots.

The result is a game where every shot feels physical and every bounce matters. You learn the physics intuitively through play — and once you understand how angles and power interact, you start finding shot lines you never thought possible.