When comparing HaxePunk vs UDK, the Slant community recommends HaxePunk for most people. In the question“What are the best 2D game engines?” HaxePunk is ranked 22nd while UDK is ranked 73rd. The most important reason people chose HaxePunk is:
Useful for mobile games and soon consoles (OpenFL has a console port in the works).
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Joystick and multi-touch support
Useful for mobile games and soon consoles (OpenFL has a console port in the works).

Pro Crossplatform testing/releasing
HaxePunk uses OpenFL which means you can compile to just about every device. A lot of the rendering code has been optimized so if you use HaxePunk’s graphic classes you are pretty much ready to deploy on any target.
Pro Generic entity system
A generic Entity system that only uses what you “attach” to it. If you need collision masks they are available but if an entity doesn’t need to collide with anything then simply don’t add a mask. Same goes for graphics.
Pro Written in Haxe instead of AS3
This comes with blazing fast compile times, proper static typing, multiple output targets, and a powerful macro system.
Pro Multiple collision masks
HaxePunk has added several collision masks beyond what FlashPunk had including a grid with slope values, circles, and polygons. This is in addition to FlashPunk’s tile grid and hitbox.
Pro Tweens
Tweens are available just like they are in FlashPunk. If you need to interpolate values for sounds, movement, etc… it’s probably already available as a tween. There is also a VarTween that lets you interpolate any value you want.
Pro Large toolset
UDK has an extremely large toolset that allows creating almost anything without having to use a 3rd party tool or plugin.
Pro Triple A track record
UDK is an engine used by many big name companies for popular games such as the Gears of War series.
Cons
Con Messy / fragmented documentation
Not a lot of documentation is available.

Con Small comunity
It’s a small but growing community.
Con Superseded by Unreal Engine 4
Con DevKit only runs on Windows
Even though UDK can deploy games to run on multiple platforms, including Mac, it does not feature support for development on Mac.
Con Limits games to FPS
UDK was originally developed for the FPS, "Unreal Tournament", and it certainly shows. While UDK is a very powerful engine, it takes quite a bit of work to make it do something other than an FPS.
