Godot is a popular open source 2D/3D game engine. If you are interested in learning more I did a closer look review as well as a complete tutorial series. They just released Godot 2.0.4 in advance of the soon to be released 2.1.
From the 2.0.4 release notes:
- Many new classes documented! Thanks to all those that got involved after our call for contributors! Feel free to join us as there's still a lot to do, but the progress is heart-warming!
- Updated libraries: GLEW 1.13.0, libogg 1.3.2, libvorbis 1.3.5, libtheora 1.1.1, libpng 1.5.27
- Ability to rotate controls using tool
- Added classes' short descriptions as tooltips in the create dialog
- Added 'fat' option for bits param on scons for osx, produces a binary containing both 32 bits and 64 bits binaries
- Change low processor usage mode to cap to 60 FPS rather than 40 FPS
- Change the default comment color to #676767
- Debugger: show error message if description is not available
- Dynamic property list for control margins allowing floating point properties to be used with ratio anchors
- iOS: added "arch" parameter, made iphone use it to build isim
- OSX: Key modifiers (Ctrl, Alt, Meta and Shift) may be used as Input keys now
- OSX export: Default to fat format, make it an enum
str() for arrays
- The create dialog starts collapsed now. The original behavior can be reactivated in the editor settings
- Various enhancements to the script editor, such as member variables highlighting, breakpoint markers, caret blinking, etc.
- Avoid crash if setting modifiers fails
- Avoid mirroring to go negative to fix crash
- Change invalid characters when get user data dir on Windows & Unix
- Correctly parse utf8 from zip_io open, also fixes issues when exporting or opening android apk files
- Editor: Fix base dir when going back to project manager
- Fix a inherited transform bug with Camera2D preview drawing
- Fix bug in
- Fix crashes in code completion and SamplePlayer
- Fix error storing path for children of instanced nodes in .tscn
- Fix errors while exporting to Android
File.get_as_text() to return the whole file
- Fix OpenSSL connections on 64-bit Windows
- Fix own world option of Viewport
- Fix parsing of floats in scientific notation
- Fix several bugs related to node duplication and signals
- Fix Theora video playback without a Vorbis stream
- Fix unsaved modifications in scripts being overwritten on filesystem changes
- Fix visual server error when minimizing the window
- Fixed ancient bug that prevented proper theme editing
- Fixed bug using DirAccess in Android Marshmallow due to data dir being a symlink
- Fixed various bugs with inner classes
- LineEdit: Fix and improve selection behaviour
- Make Input Actions config not affect the editor
- Properly deliver localized coordinates when passing gui events through parents
- Resolve numerical error when comparing instancing an inheritance to avoid wrongly saving unchanged properties
- Windows: prevent freeze while moving or resizing the game window.
- And many other nice changes that we can't possibly list here without boring you to the end of times!
Godot is available for download here. Stay tuned for the 2.1 release which should arrive any day now.