AppGameKit Classic is described as 'AppGameKit is a simple cross platform game development tool that runs on Windows, Linux, MacOS and Raspberry Pi. A version to run on Android and iOS is also available' and is an app in the Development category. There are more than 50 alternatives to AppGameKit Classic for a variety of platforms, including Windows, Mac, Linux, iPhone and Android. The best alternative is Godot Engine, which is both free and Open Source. Other great apps like AppGameKit Classic are Unity (Free Personal), LÖVE (Free, Open Source), Cocos2d-x (Free, Open Source) and GameMaker: Studio (Paid).
Godot is a fully featured, open source, MIT licensed game engine. It focuses on having great tools, and a visual oriented workflow that can export to PC, Mobile and Web platforms. It is a cross-platform 2D and 3D game engine and game development IDE.
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.
Panda3D is a game engine, a framework for 3D rendering and game development for Python and C++ programs. Panda3D is Open Source and free for any purpose, including commercial ventures, thanks to its liberal license. Go ahead and grab it here.
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.
Pygame is a set of Python modules designed for writing video games. Pygame adds functionality on top of the excellent SDL library. This allows you to create fully featured games and multimedia programs in the python language.