When comparing Phaser.io 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 Phaser.io is ranked 8th. 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 Built-in Arcade Particle system
Pro Great community resources
Pro WebGL and Canvas rendering modes
You can choose WebGL or classic HTML canvas element for game rendering.
Pro Very active development
This is one of the most developed frameworks right now.

Pro Good tutorials, courses and books
There are plenty of great learning resources available for Phaser.io.
Pro Super-simple loading of assets
Pro Excellent tools for sprites
Pro Support for Arcade Physics, Ninja Physics and p2.js
Pro Easy to learn
Most tasks are done just using 2 or 3 lines of code.


Pro Very fast to develop with
If you're browsing Slant, you probably already have a JavaScript enabled browser, which is most of what you need to get started learning JavaScript. The requirement to run a server locally on your computer while developing might make things a little more difficult
Pro No install required
All you need to do is attach Phaser script to a HTML page even without installing any extensions.
Pro Easy to understand if you have used flash
Phaser provides a similar approach as to that of Flash games, where you can load assets and place them on a stage, and even improves upon the shortcomings of actionscript. It is very easy to shift from flash to HTML5 development because of this approach.
Pro You can run it in the cloud
You can use it in popular online editors like replit, codandbox, etc.
Pro Animating is easy
Pro Has separate versions maintained by developer and the community
The creator of phaser(photonstorm) has given the older(Phaser 2.0) source code to the community for their own maintenance, and has made Phaser 3.0 with a different style and approach, trying to make it easier for beginners to learn.
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 Using Cordova to Export for Mobile
To export to mobile games you need to use cordova.
Con Official documentation is not so good

Con Poor performance
As long as your map is not larger than 600*400px, everything is fine.
Con Extremely many bugs
Con Developer ignores community needs
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.
