Awesome

:heavy_dollar_sign: = Paid, :triangular_flag_on_post: = Limited Free, :free: = 100% Free, :o2: = Open Source

Please remember to always look at the license before using something in your project.

Assets
Code
Design
Meta
Tutorials

Assets

2D Assets

:free: 2D Cartoon Mobile Game UI Pack - cartoon user interface asset pack. It comes as a layered psd file.
:free: 420 Pixel Art Icons for RPGs - Set of 420 RPG icons, free for commercial use.
:heavy_dollar_sign: GameartGuppy - Cheap 2D Assets
:free: Games-Icons Set - free icons for your games.
:free: Iconmonstr - Another free icons resource for your games.
:triangular_flag_on_post: Kenny Assets - Royalty free assets
:free: OpenClipart - Collection of free cliparts.
:heavy_dollar_sign: Oryx Design Lab - Cheap high quality royalty free sprites
:free: SpriteLib - a collection of static and animated graphic objects (also commonly known as sprites).
:triangular_flag_on_post: Time Fantasy - Lovely SNES-Looking RPG Assets

3D Assets

:free: Blender 3D models - 3D models, particle systems/effects
:free: Matcaps - A Huge library of matcap textures in PNG and ZMT, organized by color.
:free: Poly Pizza - Searchable library of low poly creative commons 3D models
:free: Reiner's Tilesets - A blog with free 2D and 3D graphics.
:free: 3DModelsCC0 - Public domain 3D models

Audio Assets

:free: GameSounds - Archive of all kinds of royalty-free game sounds.
:free: FreePD - Public Domain Music
:free: FreeSFX - free sound effects
:free: Freesound - collaborative database of Creative Commons Licensed sounds
:free: Kavex's GameSounds - Free sounds for any use
:free: Musopen - Royalty free music.
:heavy_dollar_sign: Nameless: the Hackers RPG Soundtrack - high-quality by BoxCat Games
:free: Octave - free library of UI sounds, handmade for iOS.
:free: PacDV - royalty free sounds collection.
:free: SoundBible.com - Royalty-free of sound effects under various licenses.

Multiple Graphic Collections

:triangular_flag_on_post: CGTextures - A large collection of textures.
:heavy_dollar_sign: GameDev Market - a community-driven marketplace that connects indie game developers with talented asset creators.
:triangular_flag_on_post: LotPixel - A huge assets library. Photogrammetry and PBR Textures, 3D Models, Decals. 1500+ Free Texture Available.
:free: OpenGameArt - a media repository intended for use with free software game projects.
:free: PlainTextures - Free high resolution textures, brushes and photos
:triangular_flag_on_post: Sketchfab - Publish & embed interactive 3D models.
:free: Vecteezy - Free Vector Art.

Code

Ads and Monetization

AdMob by Google - Google's Ads and monetization service for mobile.
Appodeal - A programmatic ad mediation solution for mobile apps.
Unity Ads - Unity3D Official Ads SDK.

2D Engines and Frameworks

:o2: Allegro - Allegro 4 & 5 are cross-platform, open source, game programming libraries, primarily for C and C++ developers.
:o2: Bladecoder - Classic point and click adventure game engine and editor.
:o2: Box2D - A 2D Physics Engine for Games.
:o2: Chipmunk C# - C# implementation of the Chipmunk2D lib.
:o2: Chipmunk2D - A fast and lightweight 2D game physics library.
:o2: Cocos2D - graphic library for games and multimedia, for python language
:free: Cocos2d-x - a C++ OpenGL 2D and 3D game engine. Uses C++ but has JS and Lua bindings.
:triangular_flag_on_post: Construct 2 - an HTML5 game maker, meaning you are not actually writing JavaScript. Instead, you use actions, events and conditions to do the heavy lifting.
:o2: Coquette - A micro framework for JavaScript games. Handles collision detection, the game update loop, canvas rendering, and keyboard and mouse input.
:free: Defold 2D game engine by King
:free: EasyRPG - role playing game creation tool compatible with RPG Maker 2000/2003 games
:o2: ENGi - A multi-platform 2D game library for Go.
:o2: Ejecta - A Fast, Open Source JavaScript, Canvas & Audio Implementation for iOS.
:o2: EnchantJS - A simple JavaScript framework for creating games and apps (old).
:heavy_dollar_sign: GameMaker - Very good 2d engine if you are only interested in 2d
:heavy_dollar_sign: GameSalad - Game Creation Engine for Mac and Windows.
:o2: Gideros - Mobile Cross-Platform framework using Lua programming language.
:o2: Glide Engine - Game engine for making 2d games on iOS, macOS and tvOS, with practical examples.
:o2: Gosu - 2D game development library for Ruby and C++
:o2: HaxeFlixel - Create cross-platform games easier and free in Haxe.
:o2: HEAPS.io - A mature cross-platform graphics engine for high performance games written in Haxe.
:o2: iio.js - A javascript library that speeds the creation and deployment of HTML5 Canvas applications
:o2:JNGL - 2D C++ Cross-Platform engine for Nintendo Switch, Xbox, Linux, Windows, OS X, Web, Android, iOS and more.
:o2: Juno TypeScript - Clean and lightweight 2D game framework written in TypeScript
:o2: Kivent - A 2D game framework for Kivy.
:o2: Kivy - Cross platform Python framework for creating apps and games for Linux, Windows, OS X, Android and iOS
:o2: LibGDX - Powerful (totally free) library for Java, code once and run the game on desktop, Android, Web, and iOS.
:o2: Lums - A 2D / 3D framework written in C++11. Very efficient and modern. Still under heavy development.
:o2: LÖVE - Lua 2D Game Engine, very good game jam engine.
:o2: MINX - Open Source 2D game framework written in C++ (to the style of XNA)
:o2: Matter.js - a 2D physics engine for the web.
:o2: MelonJS - open source light-weight HTML5 game engine.
:o2: Monogame - Open Source implementation of the Microsoft XNA 4 Framework.
:free: NodeBox - a family of Python tools to create generative design.
:o2: OpenFL - Open Source Haxe Engine for making multi-platform games.
:o2:OpenRA - OpenRA is a Libre/Free Real Time Strategy Game Engine.
:o2:ORX - ORX is a 2.5D Data-driven C/C++ open source & multi-platform Game Engine.
:heavy_dollar_sign: PICO-8 - A fantasy console for making, sharing and playing tiny games and other computer programs.
:o2: PandaJS - Open Source HTML5 Engine.
:o2: Phaser - free and fast 2D game framework for making HTML5 games for desktop and mobile web browsers, supporting Canvas and WebGL rendering.
:o2: PixiJS - is a newcomer HTML5 game renderer - first released in early 2013. A main appeal of the engine is its use of WebGL for faster performance. If WebGL isn't supported, the engine falls back to standard canvas.
:free: PuzzleScript - open-source HTML5 puzzle game engine.
:o2: PyGame - a 2D game engine in Python.
:heavy_dollar_sign: RPGMaker - series of programs for the development of role-playing games.
:free: Ren'Py - visual novel engine using the Python language in simplified form. It supports Windows, Mac OS X, Linux, Android and iOS
:free: SDL - SDL is a cross-platform library designed to provide low level access to audio, keyboard, mouse, joystick, and graphics hardware via OpenGL and Direct3D.
:free: SFML - Simple and Fast Multimedia Library.
:o2: Solar2D - A Cross-Platform Mobile App Development for iOS and Android (corona).
:free: Solarus a free and open-source Action-RPG (Zelda) game engine
:o2: SpriteBuilder - Open Source Game Development Suite for MacOS
:free: SpriteKit - SpriteKit code to make your game work on iOS, macOS, and tvOS without a hitch.
:o2: Stage.js - Lightweight and fast 2D HTML5 rendering and layout engine for cross-platform game development.
:free: Stencyl - a game creation platform that allows users to create 2D video games for computers, mobile devices, and the web.
:o2: Tilengine - C Engine with wrappers for C#, Python and Java.
Tiny Computer - open source fantasy computer for making, playing and sharing tiny games.

3D Engines and Frameworks

:free: Azul3D - A 3D engine written in Go.
:o2: bgfx - Cross-platform, graphics API agnostic, "Bring Your Own Engine/Framework" style rendering library.
:o2: Bevy - A data-driven game engine in the form of a Rust library.
:o2: Bullet - Real-time physics simulation.
:o2: Cinder - Cinder is a community-developed, free and open source library for professional-quality creative coding in C++.
:o2: Dash - A free and open 3D game engine written in D.
:o2: Diligent Engine - A modern cross-platform low-level graphics library that supports Direct3D11, Direct3D12, OpenGL/GLES, and Vulkan.
:free: Evergine - The graphics development engine for business and industry. Build high-quality 3D solutions and deploy to any platform.
:o2: :triangular_flag_on_post: Flax Engine - multi-platform 3D game engine
:o2: gameplay3d - 2D + 3D game framework written in C++
:o2: Godot - An advanced, feature-packed, multi-platform 2D and 3D open-source game engine.
:o2: Horde3D - small open source 3D rendering engine.
:o2: Irrlicht - open source high performance realtime 3D engine written in C++.
:o2: jMonkeyEngine 3 - a 3D open-source game engine for adventurous Java developers.
:free: JPCT - jPCT is a 3D engine for desktop Java and Google's Android.
:o2: Amazon Lumberyard - Amazon Lumberyard is a free AAA game engine deeply integrated
:o2: ODE - ODE is an open source, high performance library for simulating rigid body dynamics.
:free: Ogre3D - is a scene-oriented, real-time, flexible 3D rendering engine (as opposed to a game engine) written in C++.
:triangular_flag_on_post: OpenXRay - a community-modified X-Ray engine used in S.T.A.L.K.E.R. game series.
:o2: Panda3D - a framework for 3D rendering and game development for Python and C++ programs.
:o2: Piston - a modular open source game engine written in Rust.
:free: PlayCanvas - A WebGL Game Engine with limited free
:o2: Rajawali - Android OpenGL ES 2.0/3.0 Engine
:o2: Raylib - A simple 2D and 3D graphics library, with bindings available in numerous programming languages.
:free: Source Valve's Flagship engine
:free: Spring - A powerful free cross-platform RTS engine.
:heavy_dollar_sign: Stingray - 3D game engine and real-time rendering software
:free: Superpowers - HTML5 Collaborative 2D/3D Game Maker
:o2: Three.js - Javascript 3D Library.
:free: Turbulenz - Turbulenz offers the ability to build, publish, iterate and monetise high-quality games that react like no others, with immersive 3D effects and real-time physics that open up a whole new world of unprecedented and extraordinary web content.
:free: Unity 3D - A development engine for the creation of 2D and 3D games and interactive content.
:free: Unreal Engine 4 - the new game engine technology developed by Epic Games.
:o2: Urho3D - Cross-platform rendering and game engine.+
:o2: WhiteStorm.js - 3d javacript framework for building apps and games
:free: voxel.js - voxel.js is a collection of projects that make it easier than ever to create 3D voxel games like Minecraft all in the browser.
:o2: Xenko Game Engine - open-source C# game engine designed for the future of gaming

Game Source Code

:o2: BrowserQuest
:o2: Diablo
:o2: Doom 3
:o2: Doom
:free: Duke Nukem 3D: Atomic Edition
:heavy_dollar_sign: HandmadeHero: making 2D game from scratch
:o2: Prince of Persia
:o2: Quake 2
:o2: Quake III Arena
:o2: Quake
:o2: SimCity
:o2: Wolfenstein 3D
:o2: Delver

Modules and Additional API

:free: AirConsole- Add controller support using broswer
:o2: DotRecast - a port of Recast & Detour, navigation mesh toolset for games, Unity3D, servers, C#
:o2: ecs-lib - ecs-lib is a tiny and easy to use ECS (Entity Component System) library for game programming. It's written in Typescript but you can use on node.js and web browser too.
:o2: kitlang - Kit is a programming language designed for creating concise, high performance cross-platform applications.
:o2: p2.js - JavaScript 2D physics library
:o2: SimpleAI - C++ AI behaviour tree based library with a QT5 based remote debugger

Design

Idea Generators

:free: Boardgamizer - Board Game Design Idea Generator.
:free: Gigster Randomized Game Idea Generator
:free: RPTools - a brand of open-source programs designed to enhance traditional pen-and-paper role playing games.
:free: Video Game Name Generator Randomized video games names

Marketing and PR

:free: Yunoia - Online Publishers/Marketing

Mechanics

:free: Board Game Mechanics Set of different board game mechanics

Project Management

:triangular_flag_on_post: Asana - Free cloud project Management
:triangular_flag_on_post: Casual - Visual Project Management
:triangular_flag_on_post: ClickUp - One app to replace them all.
:heavy_dollar_sign: Codecks - Project Management Tool inspired by Collectible Card Games
:triangular_flag_on_post: HacknPlan - Project management for game developers
:triangular_flag_on_post: Taiga - Project management platform for agile developers & designers
:triangular_flag_on_post: Trello - Organize and prioritize projects

Tools

Animation

:heavy_dollar_sign: Fusion Character Animator - small tool for Clickteam Fusion 2.5 to facilitate the animation of 2D character sprites for developers.
:o2: ScreenToGif - record a selected area of your screen and save it as a Gif
:heavy_dollar_sign: Spine - Spine is dedicated to 2D animation, providing an efficient workflow both for creating amazing animation and for integrating it into your games.
:o2: DragonBones - The Open Source 2D skeleton animation solution for Flash
:o2: LWF - Lightweight SWF. LWF is an animation engine which can play animation data converted from FLASH contents in HTML5, Unity, Cocos2d-x, iOS UIKit, and more.

Audio Tools

:o2: Ardour - A multichannel digital audio workstation
:o2: Audacity - cross-platform software for recording and editing sounds.
:free: BeepBox - online tool for sketching and sharing chiptune melodies
:free: Bfxr - A tool to make sound effects for computer games.
:free: Bosca Ceoil - Online (and also desktop) music producer made by Terry Cavanagh. Simple, intuitive, has a distinctive retro-ish sound.
:free: ChipTone - Online sound effect generator
:free: FamiTracker - Produce music for the NES/Famicom-systems
:free: jfxr - A JavaScript port of the Bfxr sound effect generator.
:o2: LMMS - digital audio workstation software
:free: MadTracker - a powerful and efficient approach to making music. Versatility and compatibility are guaranteed due to full VST™, ASIO™ and ReWire™ support.
:o2: Musagi - fairly large and sophisticated music editor and synthesizer
:free: PulseBoy web-based musical sequencer which only uses 8bit sounds and samples
:o2: Rosegarden - music composition and editing environmen
:o2: Sekaiju - Open Source MIDI sequencer.
:heavy_dollar_sign: Soundation - Online Professional music studio.
:free: SunVox - a small, fast and powerful modular synthesizer with pattern-based sequencer (tracker).
:o2: Unity-Audio-Manager - Plugin, that allows to easily play/change/stop/mute/... sounds in 2D/3D

Bitmap Compression

:free: ImageAlpha — Mac OS X GUI for pngquant and other tools
:o2: Image Asset Generation Photoshop plug-in — Easy export layers to files.
:heavy_dollar_sign: Kraken.io - robust, ultra-fast image optimizer and compressor with best-in-class algorithms.
:free: PNGGauntlet - Smash PNGs for faster sites
:free: PNGoo - Windows GUI for batch conversion.
:o2: Pngyu - simple PNG image file compression tool.
:free: SuperPNG Photoshop plug-in — Mac and Windows. Comparison with "Save for Web"
:free: TinyPNG - Advanced lossy compression for PNG images that preserves full alpha transparency.

Character Generators

:free: Charas - Charas is a charset generator for RPG Maker.

Design Tools

:heavy_dollar_sign: articy:draft visual environment for the creation and organization of game content.
:free: Dundoc Game Design starter Template
:heavy_dollar_sign: Scrivener Helps concentrate on composing and structuring long and difficult documents
:free: Tiny Game Design Tool small, portable booklet created in order to help game designers.
:o2: Twine - Open-source tool for telling interactive, nonlinear stories.

IDE and Editors

:o2: Atom Highly customizable open source text editor
:free: CodeLobster - free cross-platform integrated development environment
:free: Eclipse - integrated development environment mainly used for Java
:o2: Notepad++ Notepad replacement that supports several languages.
:heavy_dollar_sign: Sublime Text Sophisticated text editor for code, markup and prose.
:free: Visual Studio Code Free. Built on open source. Runs everywhere.
:free: Visual Studio Community Edition A fully-featured, extensible, free IDE

Material

:o2: Material Maker - Material Maker is a procedural materials authoring tool based on the Godot Engine.

Modeling

:o2: Blender - free and open source 3D creation suite
:free: ZBrush Mini digital sculpting software
:heavy_dollar_sign: SketchUp - 3D modeling computer program for a wide range of drawing application
:heavy_dollar_sign: Maya Industry animation software
:heavy_dollar_sign: 3ds Max Industry modeling software
:triangular_flag_on_post: Clara.io - Start creating, rendering and sharing 3D

Pixel Editor

:heavy_dollar_sign: Aseprite - Animated sprite editor & pixel art tool
:heavy_dollar_sign: Hexels - intuitive 2D, grid-based painting tool
:heavy_dollar_sign: Pickle - Another Pixel art Editor.
:o2: PiskelApp - Free Online Pixel Art and Animated Sprite Tool.
:free: Pixa.Pics - Load any image on the web app as a pixel art. Then, draw, and eventually vectorize art.
:free: Pixi Paint Desktop version of Pixie Engine
:free: Pixie Engine - Free online pixel editor
:free: Pixelicious - Image-to-Pixel Art converter
:heavy_dollar_sign: Pixen - Pixel Art Editor for OSX (Warning: Pixen previously did not support custom gif palettes before becoming paid, and may still have this limiation.)
:heavy_dollar_sign: PyxelEdit - Pixel art editor designed to make it fun and easy to make tilesets, levels and animations.

Spritesheet

:o2: Cheetah-Texture-Packer - High efficient and fast 2D bin packing tool
:free: GlueIT Free Simple Spritesheet Tool
:free: Leshy SpriteSheet Tool - HTML5 tool for creating, packing, and modifying sprite sheets and texture atlases
:o2: Libgdx Texture Packer - Texture Packer built into Libgdx
:free: MakeAtlas - Simple tool to pack a texture atlas
:free: ShoeBox - Adobe Air based app with game and ui related tools.
:triangular_flag_on_post: SpriteUV2 - tool for creating optimal meshes for textures/sprites and packing them into an atlas.
:o2: Stitches An HTML5 sprite sheet generator
:heavy_dollar_sign: TexturePacker - Great spritesheet creation editor.

Story Design

:free: RapidQuest Free Branching Quest design tool

Terrain Generators

:free: Canyon Terrain Editor - Create quality, realistic terrain quickly and intuitively
:free: Fracplanet - Fractal planet and terrain generator
:heavy_dollar_sign: World Machine - Procedural terrain creation, simulations of nature, and interactive editing

Texturing

:heavy_dollar_sign: FilterForge - A plugin for Adobe Photoshop that allows you to build your own filters.
:heavy_dollar_sign: PixPlant - Smart 3D texturing tool that creates high quality normal, displacement, specular maps and seamless textures from photos.

Tile/Level Editors

:o2: OGMO Editor - generic level editor.
:free: Mappy - Free tilemap editor.
:free: Sprite Fusion - Free tilemap editor running in the browser, export your tilemaps as native Unity Packages and Godot Maps.
:free: Tiled - free, easy to use and flexible tile map editor.

Vector/Image Editor

:o2: Gimp - GNU Image Manipulation Program. It is a freely distributed piece of software for such tasks as photo retouching, image composition and image authoring.
:o2: Krita - Sketching and painting, offering an end-to-end solution for creating digital painting files from scratch by masters.
:o2: Inkscape - Inkscape is a free and open-source vector graphics editor for traditional Unix-compatible systems such as GNU/Linux, BSD derivatives and Illumos, as well as Windows and macOS.
:free: Paint.NET - Paint.NET is free image and photo editing software for PCs that run Windows.
:heavy_dollar_sign: Pixelmator - Full-featured image editing app for the Mac
:heavy_dollar_sign: Affinity Designer - Professional graphic design software, easy to use and fast
:heavy_dollar_sign: Affinity Photo - Professional photo editing software

Voxel Editors

:o2: goxel - Open source 3D voxel editor
:o2: VoxelShop- Open source for modify and create voxel objects

Bug Reporting

:triangular_flag_on_post: Instabug - Bug Reporting tool for Unity that enables beta users to send feedback in-app.

Tutorials

Game Development Tutorials

:free: 3D Game Shaders For Beginners - Step-by-step guide to real-time shading techniques.
:free: Simple HTML5 Canvas Game - Simple HTML canvas RPG looking game
:free: Udacity: HTML5 Game Development - HTML5 Game Development by Google

A selection of major game studios, publishers, etc. using GitHub:

More games on Github