When comparing Urho3D 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 Urho3D is ranked 61st. 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 Free and fully open source
The entire engine is open source and makes use of other open source libraries. Source code is licensed under MIT and available on GitHub.
Pro Good documentation
The documentation for Urho3D can be split in two parts: auto-generated from class references and documentation written to cover the various aspects, features and systems of the engine. The written documentation is pretty good. It covers most of the aspects of the engine in clear and understandable English.
Pro Includes a lot of samples
There are a lot of sample projects included with the engine for both C++ and Angelscript. They are mostly very simple applications built to demonstrate the engines capabilities and features.
Pro Fat-free codebase
Only use what you need.
Pro Small turnaround times while developing
Builds are quite fast, aids in rapid development.
Pro Very high code quality
Urho3D is written in a modular and super-clean way, so that it can be integrated into the other parts of your game seamlessly.
Pro Good 3D level editor
Pro In constant active development
Bugs are usually fixed that same day. Core devs are very active on forums. New features are always being worked on. HTML5, DirectX11, and OpenGL3.1 support have recently been added (as of 4/15/15).
Pro Does not require an editor to get going
Pro Flexible rendering pipeline
You can configure rendering pipeline.
Pro Multi-Lights
There are no lights limits per mesh.
Pro Unofficial Oculus Rift support
Information on enabling OR support can be found here.
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 It has been stopped developing
The owner has moved to build new 3D engine, however, that is also experimental stage, not for production.
Con Little documentation and small community
There are some high-level design docs and a bunch of examples, but code is poorly commented and nothing much more can be found.
Con The UI can be hard on the eyes
Urho3D's UI could cause eye strain.
Con There is no support for reflections
Neither SSR nor cubemap parallax correction are implemented in engine.
Con Bad Android support
You can not compile this engine using latest Android Studio.
Con May be a bit hard to get started
To install Urho3D you need to get the archive from GitHub (be careful to download the master branch) and extract it. After that, you need to compile the engine with CMake. If all the dependencies are installed, then it should be a straightforward process, otherwise you will need to track down and install all the missing dependencies.
For people who don't have much experience with CMake this whole process may seem a bit like magic. For people who do have experience with CMake, the whole installation will be relatively easy.
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.
