When comparing MonoGame vs Defold, the Slant community recommends MonoGame for most people. In the question“What are the best 2D game engines?” MonoGame is ranked 9th while Defold is ranked 21st. The most important reason people chose MonoGame is:
Support for iOS, Android, Mac OS X, Linux, Windows (both OpenGL and DirectX), Windows 8 Store, Windows Phone 8, PlayStation Mobile, PlayStation 4, Xbox One, Nintendo Switch, and the OUYA console with even more platforms on the way.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Cross-platform
Support for iOS, Android, Mac OS X, Linux, Windows (both OpenGL and DirectX), Windows 8 Store, Windows Phone 8, PlayStation Mobile, PlayStation 4, Xbox One, Nintendo Switch, and the OUYA console with even more platforms on the way.
Pro Open source
All the code is available to you ensuring you'll have the ability to make changes when you need to or even port to whole new platforms.
Pro Well-known and documented API
The framework implements the XNA 4 API, so games made in XNA can be ported to other platforms using this. This was the same API used by the Xbox Live Indie Games platform so there's lots of documentation online for it.
Pro Managed code
By leveraging C# and other .NET languages on Microsoft and Mono platforms you can write modern, fast, and reliable game code.
Pro Good community
The community MonoGame has to offer is helpful and mature.
Pro Performance on desktop
The performance on desktop platforms matches that of C++, but you still get all the pleasant features that C# has to offer.
Pro Easy to learn
Defold uses Lua, which is regarded as an easy to learn language by most.
Pro Completely free of charge
Software and online dashboard are free of charge.
Pro Good combination of visual editing + code (Lua)
You can do a lot with drag and drop, but you're not limited -- the code (Lua, which is easy to learn) allows you more power than just visual editing usually gives you.
Pro Fast results
Going from idea to result is very important for the creative process.
Pro Visual editor
Pro Very performant
Being crossplatform it is important to work on low end devices.
Pro Easy and fast export for various platforms
Pro Great community
A very active and friendly community in forums.
Pro Source code available
You can download and modify the source code of the Editor and the engine for free.
Pro Collaborative
You can invite friends from the dashboard and create games together.
Pro Hot reload
It allows you to change scripts in a game while it is running live. Common use-cases is to tweak gameplay parameters or to perform debugging on a running game.
Cons
Con Slow rate of updates
Versions 3.9 is overdue by a year, and version 4.0 is set to release in 2040.
Con Non-Windows tools are a bit funky
Monogame support for Xamarin Studio or Monodevelop is a bit shaky especially for library references. Only good non-Windows IDE compatible with MonoGame is Rider and that costs money & isn't open-source.