When comparing Genome2D vs Melharfi, the Slant community recommends Genome2D for most people. In the question“What are the best 2D game engines?” Genome2D is ranked 47th while Melharfi is ranked 108th. The most important reason people chose Genome2D is:
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
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Pros

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 :)
Pro Haxe!
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
Pro Mouse events built-in
All objects/graphics have a mouse events like MouseClic MouseDoubleClic MouseDown MouseUp MouseOver MouseMove MouseOut
Pro Network support
Lidgren Network Library
Pro Path finder built-in
Uses the A* algorithm or pathfinding
Pro GUI
It use a GDI to draw on windows forms. You can use all windows self GUI (controls) for your game like TextBox, Button Label ..., you don't need to install a third party or use an ugly controls.
Cons
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.
Con Not too many games to showcase it
Con Slow development rate
