When comparing Loom SDK vs PlayMaker + Unity3D, the Slant community recommends Loom SDK for most people. In the question“What are the best 2D game engines?” Loom SDK is ranked 45th while PlayMaker + Unity3D is ranked 77th. The most important reason people chose Loom SDK is:
Loom can live update changes in realtime, allowing you to see them on multiple devices immediately.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Live reload of code and assets across multiple platforms
Loom can live update changes in realtime, allowing you to see them on multiple devices immediately.
Pro Powerful command line workflow
Loom Turbo ($5/mo) gives access to powerful command line tools. For example, "loom new" to make a new project, "loom run" to run it. Packaging, deploy, and live reload are done automatically for you.
Pro Open source
The Loom runtime and LoomScript compiler are open source, with code available on GitHub, allowing you to have the freedom to fix the bugs and add the features your game needs.
Pro Examples
Loom includes over 30 examples ranging from complete sample games to demos of single features.
Pro Familiar and powerful scripting
Loom's scripting language is immediately familiar if you know JavaScript, ActionScript, TypeScript, C#, or Java. Internally, it uses a proven VM technology with over 10 years of heavy use in games.
Pro Good support
Loom devs are helpful.
Pro Cross-platform
Loom can deploy to Windows, OS X, Linux, iOS, Android (including Nook, Kindle Fire and Ouya). There are also custom port available for WP8, Blackberry and consoles.
Pro Easy to use
You'll need to put more time in learning Unity + Playmaker compared to something like GameSalad. But once get the hang of it and familiarize yourself with what it's possible to build with them, it's quite easy to use.
Pro Provides access to a huge list of assets through Asset Store
For those developers who can't afford an artist, or aren't skilled enough to create their own art, Unity features an Asset Store full of a wide variety of free and paid assets that can be easily added to your game. The Asset Store has more than just music and art. It also has code and modules that can be added to your game such as unique lighting or GUI systems.
Pro Third party plugins support
A lot of third party plugins have support for Playmaker. Playmaker team also invest time to add support for a lot of third party plugins.

Pro Elegant state-based visual scripting
Instead of a single "if this then that" event list which can become very cluttered beyond the most basic behaviors, PlayMaker gives each object a list of states where only certain events are triggered, and performing an action also changes state.
This allows for a clean, simple visual representation which helps break complex logical structures into smaller pieces, making them easier to understand.

Pro Powerful
It basically can do same things as scripting in Unity.
Cons
Con Documentation is lacking
Con No visual tools support
There's no level editor, asset viewer or any other visual tools in Loom SDK. Everything has to go through command line. I think it's fine if you really like typing.
Con Comparatively high learning curve
Although C#, JavaScript, and Boo have extensive documentation available online, it could still be difficult to wrap your head around the library and Unity's component based system.
Con Limited tutorials
There are not a lot videos with Playmaker tutorials. Official text tutorials are also quite limited. Even not every action has a description on an official wiki.
Con Performance could be better for 2D
Performance can be a real issue with 2D games. Unity 3D is actually a 3D game engine, and drags a lot of overhead with it.
For mobile, one could never achieve the performance of more specialized 2D engines with Unity3D.
