In 2D games, physics concepts help you create movement and interactions that feel natural and engaging. The three most important ideas for simple game physics are velocity, gravity, and collision detection. These ideas allow you to control how objects move, fall, and interact with each other in your game world.

Velocity describes both the speed and the direction of an object's movement. When you set a sprite's velocity, you are telling it how fast to move and in which direction—such as moving right across the screen or falling downward. By updating a sprite's position every frame using its velocity, you create smooth, continuous motion.

Gravity is a force that pulls objects downward, just like in the real world. In games, you can simulate gravity by steadily increasing a sprite's downward velocity over time. This makes characters and objects fall, bounce, or land realistically.

Collision detection is the process of checking whether two objects overlap or touch each other. This is essential for gameplay, such as when a character lands on a platform, picks up a coin, or bumps into an obstacle. Detecting collisions allows you to respond with game logic—like stopping movement, triggering a sound, or updating the score.