ENIGMA Development Environment vs GDevelop

Almost full support for GML,
The ability to create and access C++ types, templates, and functions, compile DLLs and other C/C++ scripts

Support for Windows, Mac and Linux.

Enigma can support over 90% of gamemaker's GML language

besides the powerful combination between GML and C++, beginners can also use drag and dropping.

Written in C++, many features have been demonstrated running much faster than interpreted equivalents in GameMaker (up to 10-20 times faster than GM 8.1).

Changes are made daily to add new functions/fixing bugs.

A full stack trace with available cores and memory information as well as operating system and Java version including file names and number is generated whenever an exception is encountered, with a handy link to submit the issue to GitHub.

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.

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.

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.

The plugin SDK is open source, so if you want to extend it, you can.

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.

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!

GDevelop is able to create HTML5 games that can run on web browsers and be exported to iOS and Android using solutions like Intel XDK or Cocoon.JS.
GDevelop is also one of the only friendly game creator that is able to make native games for Windows and Linux, which are blazing fast and allow to make advanced games with lots of objects, effects and very large levels.

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.

GDevelop is available in many languages and even community can help in translations.

Thanks to its open source nature, GDevApp.com was built over the GDevelop engine.
GDevApp.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 GDevApp and export it to open it inside GDevelop.

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.