The browser is the game engine
HTML provides the page structure, CSS controls presentation and JavaScript runs the game rules. Many games draw their moving scene onto an HTML Canvas element. The browser redraws that canvas many times per second, creating animation in much the same way that individual frames create motion in a film.
Input becomes game state
Keyboard, mouse and touch events tell the game what a player is doing. The code records whether a direction or action is active, updates positions, checks collisions and draws the next frame. Good browser games map the same action to several input methods so the experience works on laptops, tablets and phones.
Audio needs player permission
Modern browsers usually block automatic audio until a visitor interacts with the page. That is why GamesRich starts background music after the player presses Start and provides a sound control. Keeping music quieter than effects also helps important gameplay feedback remain audible.
No installation does not mean no files
A browser game still downloads HTML, CSS, JavaScript, images and audio, but the browser stores and runs them temporarily. Smaller assets reduce waiting time and data use. Static hosting and a content delivery network can serve these files quickly without requiring an account, installer or app-store update.