Game Development Fundamentals

Understanding game development fundamentals is the foundation of this guide. Below we break it down step by step so you can act with confidence.

Before writing a single line of game code, you need a mental model of how games work. Every game — from Tetris to Elden Ring — runs the same fundamental loop: read input, update the world, render the frame, repeat.

This lesson covers the core concepts you will use in every game you build: the game loop, game state, entities and components, the rendering pipeline, and how time works in a simulation.

Game Development Fundamentals: The game loop explained

A game is not like a web page that waits for user interaction. A game is a simulation that runs continuously, typically 60 times per second. Each iteration does three things:

Process input — read keyboard, mouse, touch, or gamepad state
Update state — move entities, check collisions, apply physics, run AI
Render frame — draw everything to the screen at its new position

🔬 Demo: Basic game loop with delta time

let lastTime = 0;

function gameLoop(timestamp) {
  const dt = (timestamp - lastTime) / 1000; // seconds
  lastTime = timestamp;

  processInput();
  update(dt);
  render();

  requestAnimationFrame(gameLoop);
}
requestAnimationFrame(gameLoop);

Delta time (dt) is the elapsed seconds since the last frame. Multiplying movement by dt makes your game run at the same speed regardless of frame rate.

Fixed timestep vs variable timestep

The loop above uses variable timestep — dt varies each frame. Physics simulations can become unstable with large dt spikes. A fixed timestep accumulates time and runs physics in fixed increments:

🔬 Demo: Fixed timestep accumulator

const FIXED_DT = 1 / 60; // 60 Hz physics
let accumulator = 0;

function gameLoop(timestamp) {
  const frameDt = (timestamp - lastTime) / 1000;
  lastTime = timestamp;
  accumulator += frameDt;

  processInput();

  while (accumulator >= FIXED_DT) {
    updatePhysics(FIXED_DT);
    accumulator -= FIXED_DT;
  }

  render();
  requestAnimationFrame(gameLoop);
}

Game state and entities

Game state is the complete snapshot of your game at any moment. Entities are the objects in your world — player, enemies, bullets, platforms. A common pattern is the Entity-Component approach:

🔬 Demo: Entity-component structure

class Entity {
  constructor(x, y, w, h) {
    this.x = x; this.y = y;
    this.w = w; this.h = h;
    this.vx = 0; this.vy = 0;
    this.active = true;
  }
  update(dt) {
    this.x += this.vx * dt;
    this.y += this.vy * dt;
  }
}

class GameState {
  constructor() {
    this.player = new Entity(100, 300, 32, 48);
    this.enemies = [];
    this.bullets = [];
    this.score = 0;
  }
  update(dt) {
    this.player.update(dt);
    this.enemies.forEach(e => e.update(dt));
    this.bullets.forEach(b => b.update(dt));
    // remove inactive
    this.bullets = this.bullets.filter(b => b.active);
  }
}

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Input handling patterns

Track key state in a map so you can poll it each frame instead of relying on event callbacks:

🔬 Demo: Keyboard input tracker

const keys = {};
window.addEventListener('keydown', e => keys[e.code] = true);
window.addEventListener('keyup',   e => keys[e.code] = false);

function processInput() {
  if (keys['ArrowLeft'])  player.vx = -player.speed;
  else if (keys['ArrowRight']) player.vx = player.speed;
  else player.vx = 0;

  if (keys['Space'] && player.grounded) {
    player.vy = -player.jumpForce;
    player.grounded = false;
  }
}

When evaluating game development fundamentals, start with the fundamentals: what problem it solves, who it serves, and how it compares to the alternatives buyers consider first.

Start with the fundamentals. Define who you are serving, the single outcome you want, and the budget you are comfortable committing before you compare any options.

A practical rule is to favour clarity over cleverness. The choice that is easiest to understand, spell, remember and act on tends to win over the long run.

Context changes the answer. What is optimal for a fast-moving startup is rarely optimal for an established brand, so weigh your own stage, market and ambitions.

Avoid the common mistakes: rushing the decision, copying competitors blindly, and ignoring the total cost of ownership beyond the very first year of use.

Think in terms of trade-offs rather than a single perfect answer. Every option trades memorability, cost, reach and flexibility in a slightly different mix.

Document your reasoning. Writing down why you chose one path makes it far easier to revisit the decision later and to explain it to partners and investors.

Test with real people. A quick check with a handful of your actual customers will surface problems that no amount of internal debate ever reveals.

Plan for growth. The option that fits today should still make sense when your audience, catalogue or team is several times larger than it is right now.

Finally, revisit the decision periodically. Markets, tools and best practices move quickly, and a choice that was ideal last year may deserve a fresh look today.