SFML vs Unity 2D

In short, SFML is free for any use (commercial or personal, proprietary or open-source). You can use SFML in your project without any restriction. You can even omit to mention that you use SFML -- although it would be appreciated.

If you hate something about the way SFML handles graphics, you can just combine it with OpenGL. It's completely smooth and works as expected, without any additional dependencies.

You can ask questions on their own personal forum which is full of users, and their wiki is constantly being maintained. They even have an IRC.

SFML 2.2 brought forth Android & iOS functionality, and SFML games work on Linux, Mac and Windows out of the box, since SFML is written with OpenGL.

SFML is very well documented, even with short examples of use for many functions and modules. Furthermore, there are books like 'SFML essentials' and 'SFML for game development' which teach you how to use this library to its fullest.

If you are thinking about using OpenGL, look no further, you can open a window, and handle events in less than 15 lines, and it provides input, time, and even networking, plus alot more. It has become my favorite c++ library :D

SFML is a collection of modular, well designed libraries you can implement an engine or game on top of. The API provides tons of good documentation and is very straightforward to use. You can get a game up and running with SFML quite quickly and with minimal effort.

An SFML project's code-base is usually clean and easy to read. All public SFML classes are under the namespace "sf" so it is easy to tell which code is yours and which belongs to SFML (of course you can stop this by typing using namespace sf;).

There's support for many languages besides C++, current supported languages are: C, .NET, Crystal, D, Euphoria, Go, Java, Julia, Nim, OCaml, Pascal, Python, Ruby and Rust, and this list is constantly growing.

SFML is extremely beginner friendly and even provides pre-built libraries for your IDE of choice on Windows. Besides the fact that it's extremely well documented, they also have a set of tutorials that walk you through every module.

SFML is one of the few good C++ frameworks out there to actually make full use of the language. It's extremely well optimized and it plays well with anything you throw at it.

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.

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.

Both types of 2D animation for game development are supported in Unity’s system and can be used interchangeably in the timeline.

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.