Defold
Free game engine for development of desktop, mobile, and web games
...It ships as a full editor/IDE, combining scene editing, asset management, scripting, and build/export pipelines, so developers don’t need to assemble disparate tools themselves. Game logic is written in Lua (with optional native extensions in C/C++ when needed), and the engine uses a component-based system and a message-passing paradigm to manage object interactions — a design that promotes loosely-coupled, reactive game code rather than traditional heavy OOP. Defold is optimized for efficiency: exported games tend to have small binary size and low memory use, making it appealing for mobile, HTML5/web, and lightweight games.