Apps with '2D Game Creation' feature
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.
Drag-and-drop visual programming language and platform for learning, creating and sharing code and interactive projects.
The RPG Maker software series is a set of game creation suites aimed at easy 2D role playing game creation.
A free and easy to use retro adventure game creator for your favourite handheld video game system.
Playscii is a powerful, open-source ASCII-based art, animation, and game creation tool.
ct.js is a 2D game editor (desktop app) based on web technologies. It aims to be an extensible yet simple game-making tool, accessible for both newbies and experienced game developers.
Pocket Code allows you to create your own games, animations, interactive music videos, and many kind of other apps, directly on your phone or tablet.
Orx is an open source, portable, lightweight, plugin-based, data-driven and extremely easy to use 2D-oriented game engine. Orx is mostly written in C, but allows you to develop with it with any language that can interface to C.
ENIGMA Development Environment -- A very high level language, compiled into a less high level language.