When comparing GDevelop vs Solar 2D (formerly Corona SDK), the Slant community recommends GDevelop for most people. In the question“What are the best 2D game engines?” GDevelop is ranked 2nd while Solar 2D (formerly Corona SDK) is ranked 15th. The most important reason people chose GDevelop is:
The whole interface is intuitive and easy to learn: each part of the game can be designed using visual editors. The objects editor is used to create the objects of the game, the scene editor help you to build the levels of your game and the events editor allows to give life to the whole game without programming.
Specs
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Pros
Pro Easy to use
The whole interface is intuitive and easy to learn: each part of the game can be designed using visual editors. The objects editor is used to create the objects of the game, the scene editor help you to build the levels of your game and the events editor allows to give life to the whole game without programming.

Pro Free and open-source
GDevelop's runtime libraries are MIT licensed. It can be used freely for projects of any type and there are no royalties associated with publishing games developed with GDevelop.
Pro Powerful events system to create games without programming
No need for coding using this system which is clear and powerful: events are composed of conditions and actions. Actions are launched when conditions are fulfilled.
This is a very friendly way of making games and is still efficient for advanced usage, contrary to most other "block"/"drag'n'drop" systems.
Pro Open source plugin SDK
The plugin SDK is open source, so if you want to extend it, you can.
Pro Lots of features to build games
The engine includes pathfinding, physics engine, multitouch support, custom hitboxes, platformer engine, tiled maps, multiple layers and cameras out of the box.
All of these features can be used without programming knowledge, using the visual editors.
Pro Quickly add behaviors to objects
Prebuilt behaviors can be added to objects. This is a very efficient way to add a physics engine or make a platformer game. Lots of behaviors are included, from the most advanced (Physics, platformer, top-down movement) to really simple one (like the behavior to destroy objects when outside the screen or the one to drag objects with mouse or touch).
And you still have full controls over your game as behaviors can be modified using the events!
Pro New documentation for gd5 is good for starting
A new doc is improving for gd5 that is nice for beginners and after that you can learn more from examples. Also, gd4 wiki is still there.
Pro Constant updates
New releases and bug fixes are consistent. New updates are released anywhere within 2 weeks or 1 month from the last one. Its auto-updater also does it job very well making life a lot easier.
Pro Online version available, compatible with iOS and Android
Thanks to its open source nature, GDevelop-App.com was built over the GDevelop engine.
GDevelop-App.com is a complete game creator similar to GDevelop, available directly in your browser and compatible with iPad and most Android tablets and phone! The app is perfect for making games directly from your sofa and you can even start a game on GDevelop-App and export it to open it inside GDevelop.
Pro Multilanguage support
GDevelop is available in many languages and even community can help in translations.
Pro Very simple to use

Pro Free
Corona SDK is completely free. That includes pro-tier plugins.
Pro Corona Simulator
Corona SDK ships with Corona Simulator, which runs your game/app directly on your PC/Mac and updates every time you make changes.
It provides immediate feedback to your actions, you can see your changes right on the screen, without necessity to make build to device. Getting instant feedback really boosts tenfold prototyping and development speed.

Pro Good documentation and lots of tutorials
Pro Content scaling
It's easy to create a game that looks good on many different sized mobile devices.
Pro Live builds - update builds running on a device automatically
With the live build feature, once you have created a build and installed on a device, you get lightning fast turnaround times because any change on the code or data is updated to the devices running the game (within the local WiFi) immediately. So changes can be tested on the real hardware within a very few seconds.
What's even more impressive, this even works flawless with multiple devices running the game. You have to use it to learn how good of a feature this is while development and even more, while doing QA. Imagine fixing bugs and everyone of your QA team/friends/whoever helps to get your game done, has all changes on his device without doing anything but waiting 5 seconds - outstanding.
Pro Lua syntax
Uses the great and easy-to-learn Lua programming language.
Pro Very comprehensive API
It's very quick to get things up and running with Corona SDK. The API is extensive and while it's not 100% feature-complete with the iOS API, it's close enough that you could create tons of games and never run into a roadblock.
The API docs can be found here.
Pro Amazing learning curve
Corona does not throw photoshop-like madness full of buttons editor. You can go as fast as you want, learning and building game from ground up. Eventually, you'll learn how much corona is doing for you. But to start you don't have to master complex editor software. It's a great tool to learn to start game development if you want to learn how to program and make games. Your experience will be 100% transferable to any other Pro game engine.

Pro Cross-platform desktop and mobile
Corona works on OS X, Windows and Android (including Kindle Fire & Nook).
Pro Marketplace for 3rd party plug-ins

Pro Great community

Pro Ability to call any native (C/C++/Obj-C/Java) library
Pro Completely free
Since Corona SDK became Solar2D, it's completely free, as only some third-party plugins are paid.
Pro Open Source
Since Corona SDK became Solar2D, it's completely open source under MIT license.

Pro Well supported
Cons
Con No support for atlas/tilemap and sprite sheet
At this point, you need to separate the tileset maps or character animation sprite sheet before importing it to the engine, but the developers are working on this feature.
Con GUI is slow to load
This makes doing the simplest things, like looking at one of your maps, hard to do. In looking into this program, it can stall a PC while trying to load a sample map.
Con No 3d, not even fake 3d
This is a 100$ 2d-only game engine. You could of course use pre-rendered 3d graphics, but your games themselves will exist only in the x and y axes.
Con It's very slow
Although suggested otherwise, GDevelop doesn't compile the games - it just adds wrappers so each OS can run the HTML5 game it creates. That means it runs much, much slower than other engines that do compile games.
Con No cross-compiler
The Windows and Linux versions of GDevelop can each compile a native application; but the Windows version cannot compile for Linux, nor vice versa.
Con Optional subscription not mentioned on main site
While the engine is free and open source as stated on the main website, it does not mention that some optional features and services are actually activated through a paid subscription (two tiers: 2€ and 7€). Those features are: no nag screen shown when debugging, additional metrics available on games dashboard, access to more than 2 cloud exports per day (unlimited local export can be done without subscription, provided the right packaging tools are installed and configured), easy removal of GDevelop splash screen (can be done manually without subscription).
Con Behaviors of Objects are rather generalized
Since it has a fully GUI editor, the objects you are allowed to add in your game are pretty generalized (PhysicsObject, TiledSprite, PlatformerObject, etc). This limits the freedom of a game developer while making a game, as the object msut follow the preset behaviours imposed on it.
Con Free, but not completely
Con Making a device build requires internet connection
To build your app for the device (iOS/Android/AppleTV) Corona requires to fetch resources from online. This would include base application template and plugins. This allows not to perform local build or use Xcode or Android Studio to do a build. Even Large games/apps would build very fast with good internet connection.
Your code never leaves computed. Corona SDK would transfer some information to determine which plugins and pieces has to be transferred in order to make a final steps in build.
As a bonus - you get basically one button press to get from your Corona Simulator game to game on a device.
