When comparing Crafty.js vs Genome2D, the Slant community recommends Crafty.js for most people. In the question“What are the best 2D game engines?” Crafty.js is ranked 30th while Genome2D is ranked 58th.
Ranked in these QuestionsQuestion Ranking
Easy to learn, based on Entities and Components, the later being class-like objects that entities inherit.
Has open function binding systems, allowing easy creation of custom components.
Pro Lightning fast
It's the fastest gpu-based framework out there for flash. It's beautifully optimised. It has very low rendering latency, low level OpenGL calls that other tech simply cannot do (ie Unity) due to Stage3D, and thus can render a lot more data quicker
Pro Cross-platform mobile, desktop and web
Supports Windows, Mac OS X, Linux, iOS, Android, Web and native Flash.
And with the HTML5 export, it also potentially supports development for the Wii U :)
Haxe is a strictly typed programming language that saves development time but still compiles high performance executables, and can build for tons of different platforms (flash, c++, html5, java, c#, etc.)
Pro Access to direct draw features
Has access to direct draw features so you can make you own rendering structures (scene graphs etc).
Pro Automatic dynamic batching
Automatically batch geometries with dynamic batching techniques (by using constant buffers).
Pro Component based architecture
Con No IDE
If you like having some huge GUI akin to Gamemaker, Unreal, Unity, etc, Crafty is not for you.
Con Lacks documentation
The API documentation is minimal, there's not many tutorials and the ones that are there are very small and only cover the basics. If you want to learn how to properly use it, you have to ask the community or read the source code and figure it out.