Solar2D

Solar2D is a free development engine for creating games and apps for all kinds of platforms, including iOS, tvOS, Android, Android TV, macOS, Windows, Linux, and HTML5. The engine is based on Lua, which makes it lightweight, fast, scalable, and powerful, with ample abilities to create iterations. The engine is open source and is a fork of the Corona SDK Game engine, which is no longer actively supported or developed.

The engine allows you to add a wide variety of plugins to your developments, including ones to display ads, multimedia content, analytics data, etc. More can be added from its marketplace.

In terms of privacy, Solar2D does not track user activity. Aggregated data is not even anonymously collected, as no call is made to a server. Thanks to this, all the games you create with online mode only make network requests that you, as developers, introduce to the games.

Solar2D is completely free, with no royalties, fees, or hidden charges. Whether you're an indie developer or a large company, you'll never have to pay to use it. In addition, there are several sample games to help you better understand how the engine works and make the most of the features it offers.

So, if you're looking for a powerful, lightweight, and free development engine, downloading Solar2D is one of the best options.