When comparing Angel2D vs Monkey X, the Slant community recommends Monkey X for most people. In the question“What are the best 2D game engines?” Monkey X is ranked 27th while Angel2D is ranked 90th. The most important reason people chose Monkey X is:
Developers can make native calls directly from Monkey code. This allows access to any native functionality and platform-specific features.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Great for prototyping
The framework is focused on prototyping. It has plenty of features to speed up development. It has a console with a lua interpreter, tuning variables and function calls. GWEN is well supported. Provides a simple interface for Box2D. A simple messaging system with which entities can subscribe to to receive messsages among other things.
Pro Permissive licence and easy to extend
Angel2D is built with the idea that you the game developer should have control over the framework and be able to add features if you like. So the code is BSD-licenced and very easy to extend for anyone that has completed a basic C++ course or equivalent.
Pro Great performance
While Angel2D isn't the best performing framework out there it's certainly no slog when compared to competition. Simply by the virtue of being native it puts itself ahead of engines like Gamemaker and frameworks like Love2D.
Pro Simple interface to lua scripting
If you're not comfortable with a basic subset of C++ it is not recommended to use this framework. But the Lua scripting platform is very nice for generating actors.
Pro Very helpful and simple project set up for newcomers
Often with game engines they throw you into unfamiliar territory and let you explore for yourself. While this wouldn't be a big issue with Angel2D due to it being a very simple framework it kickstarts your game prototyping.
Pro Focused on providing convenient features
Angel was created with game jams in mind, so it's focused on providing as many convenient features as possible, but in a quickly understandable way.
Pro Cross platform
Angel can create games for Windows, the Mac, most flavors of Linux, and iOS. It uses the native build systems on each platform (Visual Studio, Xcode, Make), so you can be up and running as soon as possible.
Pro Low-level code is easily accessible
Low-level code that Angel wraps is always just an easy click away, ready to be overridden or improved.
Pro Very light wrapping on all of the libraries
A very important point that's often underestimated. This framework is designed to be removed. It's not there to provide a complete engine for you which you will have trouble moving away from. The basic interface to Box2D is very spartan. You're given the simplest of Box2D shapes, not even polygonal fixtures. This limitation (seems to be) there so that the integration with the engine is very low. You never create a physics actor with anything more complicated than an enum describing if it's supposed to be a sphere shape or box shape.

Pro Native code support
Developers can make native calls directly from Monkey code. This allows access to any native functionality and platform-specific features.
Pro Native module support
You are not restricted only to the modules you get from the official release. You can build your own stuff. Even build your own "app" module. It feels limitless. In comparison with other cross platform solutions, you actually get the translated source code and you can play with it if you want.
Pro Built-in modules for quickly building games
Monkey X has a selection of great built-in modules.
- Graphics
- Audio
- Input
- Data and Filesystems
- Networking
- Math
- Text and Strings
- Collections
- Online Services
Pro You can create custom targets
The language gives you the possibility to build your own targets. You are not limited to the targets officially supported.
Pro Low cost license fee
All target platforms for a fair one off license fee.
Pro Easy to learn
With it's Object orientation and clean syntax its a brilliant language to learn if you have never done any programming before and yet still has all the power it needs to make full games and apps.
Pro Uses a great, easy to learn language
Monkey X uses a custom programming language (called Monkey) for all its scripting needs. Monkey is rather easy to learn, it's object-oriented which will help most programmers with understanding it. It's also statically typed and uses a garbage collector, helping to avoid manual memory management.
Pro Partly open-source
The entirety of the base-language itself is open source. Commercial modules such as Mojo for non-free platforms cost a one-time fee. Though Mojo is not free for all targets, the targets for these platforms are, meaning it is possible to implement other frameworks for these targets.
The Desktop (GLFW and C++ based) and HTML5 implementations of Mojo are currently free and open source.
The language's development is completely public, and is managed via GitHub.
Pro Free HTML5 and Desktop (GLFW) target platform
The free version of Monkey X lets you compile to HTML5 or Desktop (GLFW). Other platforms such as iOS, Android (and OUYA), XNA, Flash and Windows 8 (Phone) require the paid version of Monkey X Pro.
Pro Cross-platform
Monkey X is a cross-platform game engine. It allows developers to run the same code on multiple platforms, including iOS, Android, Windows Mobile, Flash, Windows, Mac OS and Linux.
The development environment supports Windows, OS X, and Linux.

Pro Not running in its own VM
Unlike other multi-platform engines (Unity3D, Corona, etc), Monkey-X games do not run explicitly in their own virtual machines. Your code is translated into the native languages of each target platform, and then compiled as a native executable. However, just as native games, on platforms such as Android (Currently), and HTML5, games will be ran through the targeted platform's usual VM(s). That being said, you won't be dealing with a proprietary virtual machine, so you won't experience any real overhead when compared to a native game.

Pro Made by the Mark Sibly Factor
The Mark Sibly Factor denotes that a programming language will be easy to learn, fun to learn and allow any age group ( within Cognitive Reason ) to program games and great games. The Mark Sibly Factor denotes also that the games programming language you purchase will be backed by decades of compiler programming experience, game making tool programming and finally a Game Programming Language that kicks Ass.
Pro Free for commercial releases
With the free version of Monkey you are still able to create commercial HTML5 and Desktop games.

Pro Many community modules available
The community has created essential modules:
- Spine for animations
- Box2D and Chipmunk for physics
- Game frameworks such as Ignition, fantomEngine, and Flixel
- Diddy for lots of extra functionality
- FontMachine for custom bitmap fonts
- MiniB3D for 3D gaming
- And several others...

Pro Drawing Commands
Drawing commands are easier to read and edit than is manipulating scene graphs. You can immediately see in your code what's going to be drawn and in what order. Transformations are a no-brainer too.
Pro Lots of great examples
Monkey X includes over 50 examples ranging from complete sample games to demos of single features.
Pro Object oriented programming
MonkeyX is an object-oriented dialect of BASIC that's easy, clean and powerful.
Cons
Con No asset pipeline
Unlike XNA/Monogame, Gamemaker or many other similar platforms, Angel2D doesn't have an asset pipeline. The extents of the asset importing is manually loading individual files in code or naming them according to a convention to load a set of them.
Con No longer supported
Hasn't been updated in 2 years.
Con Incomplete documentation
The entire framework is technically documented at http://docs.angel2d.com/ but certain functionality isn't described in there but rather it's just a list of functions. They all have descriptive names and it should be common to run into a feature which isn't given example to in the "Introgame"-project example.
Con Abandoned by developers
Sadly this project has been abandoned by the developer. The main github doesn't see any pull requests fulfilled anymore. There's a debugline draw fix on the github that's rather simple to fix. It is recommended you pull that fork rather than the master branch. Though the simplicity of the framework still makes it a good choice for prototyping.

Con You'll have to learn a new programming language
Even though Monkey is rather easy to learn and borrows a lot of concepts from more popular languages, having to learn a new language develop games is a lot of friction for people that already know how to program in other languages..

Con The documentation is not very thorough
The documentation contains a reasonably detailed language overview, and a somewhat-generated list of the included modules, classes, and methods. Module descriptions are rather lax, but usually present. Method descriptions tend to be short, and a majority of them contain no usage snippets; most parameters have very minimal descriptions. And there are no community collaboration features to help improve it, besides GitHub.
Con The included IDE is poor
Although better IDE'S are availabe for a price, the default one is bare bones and lacks functionality
Con No real asset store
Untangling how to keep assets in the ".data" requires attention and a filenaming convention.
Con limited OS export targets with free version
Free version only targets Desktop (macOS, Windows, Linux) and HTML5, not mobile.
