When comparing BYOND vs Unity 2D, the Slant community recommends Unity 2D for most people. In the question“What are the best 2D game engines?” Unity 2D is ranked 7th while BYOND is ranked 29th. The most important reason people chose Unity 2D is:
2D game creation was a major feature request from the Unity community and was added with version 4.3. 2D is provided in both the Pro and Free distribution of Unity.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro In active development
BYOND is in active development and updates are released constantly.
Pro Easy to use
The software itself is very easy to learn and use for beginners.
Pro Helpful community
BYOND's community is relatively large and extremely helpful. Any question a beginner or an experienced user may have is quickly answered.
Pro Large Community
Fairly large player base and multiple games to play.
Pro Built into Unity 4.3+
2D game creation was a major feature request from the Unity community and was added with version 4.3. 2D is provided in both the Pro and Free distribution of Unity.
Pro Integrates with Mecanim
Mecanim brings state machines and blending to 2D bone animation. The state machine editor allows for designers and programmers to visually create a Finite State Machine (FSM) to control when animations should play. Mecanim also allows for blending so an animation can transition smoothly between two states without the need of in between frames made by an animator.
Pro Sprite Sheet and Bone based animation supported
Both types of 2D animation for game development are supported in Unity’s system and can be used interchangeably in the timeline.
Pro Easily change sprites dynamically
Usually used for character customization, programmers can change any sprite in a bone animation at runtime easily by referencing the bone and loading the new sprite from the resources folder.
Cons
Con Highly supports multiplayer, but can make solo games ready for download.
Con Exclusive programming language
The language is known as DM, and is modified using Dream Maker. It is an object oriented, interpreted language, which closely resembles C++, Java and PHP. More information available in the DM Guide.
Con Lacks critical features
- Vertices can't be animated, so you can't have ANY organic feel (like... lungs breathing).
- Parent bone can't be animated without affecting the children. This is especially impeding for organic feel, again.
- No option to show & unshow assets (or it is hidden), like for switching weapon on your character for exemple.

Con Poor script interface for texture atlases
Accessing individual sprites within an atlas texture is possible at runtime, but requires use of the Resources folder subsystem.
