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GDevelop is an open source game creation software, allowing to make games for the web (HTML5) or for Windows and Linux. No programming or coding skill is required! It is easy to use and powerful enough for advanced users.

Scirra Construct is a 2D game development engine with a focus on building games visually. No programming is required though the software uses a visual method for event handling that relies on programming concepts like variables, loops and conditions. It provides a powerful form of scripting that's as easy as clicking, dragging and dropping.

Polycode's core is written in C++ and currently runs on Mac, Windows and Linux with iOS and Android support planned in the future. All platform-specific functionality is abstracted into a cross-platform core and implemented natively on each platform, so the same C++ code will compile on each supported platform out of the box.

cocos2d-x is a cross platform open source free 2D game engine for mobile gamedev, that is fast and stable, easy to learn and use.

Stencyl is the creator of StencylWorks, a tool that has enabled creators of all all skills levels create iOS and Flash games in no time. In 2012, Stencyl will expand into Android and HTML5 game publishing.

Continuing the legacy of Mark Overmars' Animo and Game Maker, GameMaker: Studio is a proprietary game-creation system which can export to multiple platforms including Windows, HTML5, Linux, iOS, Mac and Android.Often considered the fastest and easiest-to-use cross-platform game IDE technology, GameMaker: Studio allows developers to create games in a single codebase and then publish them to run natively across a wide number of mobile, desktop, and web platforms.

One framework for creating powerful cross-platform games. The spiritual successor to XNA with 1000's of titles shipped across desktop, mobile, and console platforms. MonoGame is a fully managed .NET open source game framework without any black boxes. Create, develop and distribute your games your way.

QICI Engine is a free and opensource JavaScript library, based on free and opensource game engine Phaser, with a web-based comprehensive suite of HTML5 game making editor.

Construct Classic is a free, DirectX 9 game creator for Windows, designed for 2D games. It uses an event based system for defining how the game behaves, in a visual, human-readable way - you dont need to program or script anything at all. Its intuitive for beginners, but powerful enough for advanced users to work without hindrance.

Platinum Arts Sandbox Free 3D Game Maker is an open source free game maker, free RPG Maker, free sidescroller maker, free Machinima creator, and game design tool that makes it easy for kids and adults to create video games, maps and worlds.

Adventure Game Studio provides the tools to make your own adventure, for free! Bring your story and artwork and slot it in, and let AGS do the rest.

Open RPG Maker is a free and open source clone of features from the RPG Maker series (i.e. rpgmaker200, rpgmaker2003, rpgmakerxp), as well as many other features. All of the data files are in XML format and are easily editable with any text editor.

ENIGMA, the Extensible Non-Interpreted Game Maker Augmentation, is an open source cross-platform game development environment derived from that of the popular software GameMaker. Its intention is to provide you with a quality game creation tool and a bridge between high- and low-level programming languages. It can be used either through an IDE, namely, its sister project, LateralGM, or through a Command line interface.

GameSalad Creator is an authoring tool developed by GameSalad, Inc. (formerly Gendai Games) aimed primarily at non-programmers for composing games in a drag-and-drop fashion, utilizing visual editors and a behavior-based logic system. It is used by consumers and creative professionals such as graphic designers, animators, and game developers for rapidly prototyping, building and self-publishing cross-platform games and interactive media. The application runs on Mac OS X and can produce iPhone , web browser-based content in HTML 5, and mac applications. »