Cocos2d-x and Cocos Creator vs Skyline

25% of iPhone games are made using Cocos2d-x.

This means you will not be alone in development, and will have access to a large community. You'll know you are developing for an engine that works.

Documentation includes a programming guide, API reference, video tutorials and massive reference test code project showing all functions and giving working code to the user.

A new feature since Cocos2d-x v3.1 is support for 3D models (in your 2D game), not only this but support for skeleton animations is included too! This awesome feature allows for impressive characters in your game along with easier, more fluid and realistic animations.

It supports Lua and Javascript with full feature support.
Especially with Cocos2d-JS you can develop games cross web and native, and the native solution have great performance with JS Bindings, much better than hybrid solution.

Cocos2d-x forums are active.

Cocos2d-x is not only open source but also supported by Chukong Technologies of China and USA.

Regularly updated and adding support for the latest technologies. 2014 has already seen the release of Version 3, a new Cocos Studio development toolkit (optional) and support for new technologies like skeleton animation systems Spine and Adobe DragonBone.

Cocos2d-x is C++ based engine and it has CPU advantages for most platforms because of that. It uses polygonal mesh methods for sprite rendering for using GPU advantages. (You also use quad methods for benefit CPU).

Because it is based on Pyglet.

On top of supporting pretty much all existing platforms (except consoles), Cocos Creator (Cocos's IDE) allows you to write 1 code that runs on Android, iOS, Windows, MacOS and HTML5 (not Linux though).

Through the use of SDKBox you can easily integrate 3rd party SDKs and plugins for each version of Cocos2D (Lua, C++ or JavaScript), you just choose the SDKs to integrate and SDKBox will do the rest.

For example, if you want to add a rating plugin, you use sdkbox::PluginReview::init(); and if you want to add the Vundle Ad Network SDK, you use the one packaged in SDKBox SDKBOX sdkbox::PluginVungle::init();.

It has a built-in Python interpreter that allows for easy debugging.

Cocos Creator (Cocos' IDE) comes with scene editing, UI editor, animations & particle editors and whatnot. It's also easy to use and pretty intuitive if you read the official documentation & tutorials. Way way better than the old CocoStudio.

Hundreds of video tutorials available.

A growing community that is always helpful with dev response times averaging less then 24 hours. Often less than 12.

Skyline provides a straightforward drag and drop development environment that can be customized to suit individual preferences. Playing the game and animating the scene can be done from within the editor at any time.

Future versions will allow extending editor's functionality with plugins and offer an official way of trading custom plugins.

Skyline's commercial edition costs just £40, has no royalties or earning limitations and includes 2 activations per license purchase and a year of free updates.

Skyline can be run on a machine with 2GHz Dual Core CPU, 2GB of RAM and Nvidia's 9800 GT (or equivalent) GPU. While, obviously, higher specs are recommended, it's reasonable to expect around 60fps on small scenes with these specs.

The Terrain editor is easy to use and will include features such as hole cutting.
There is a differed lighting render for internal scenes, which makes creating multi light and beautiful/atmospheric scenes so much easier.

All the tools for the terrain are in one place such as placing road/paths, vegetation, billboards, and the settings are easy to locate and change.

Planned features include:
Hole cutting in terrain and
Terrain paging.

Making a game in the current top engines is hard work, making something small and basic in Skyline is not. Easy to learn drag an drop model placement and editing supplemented with easy to follow video's on forum make the process straightforward.

Including image based lighting.

A free version that's limited to non-commercial usage and lacks a few features is available.

Rendering of a water plane looks fantastic and is easily edited for different effects.

The schematic editor is designed to make it easier for non-programmers to create games.

Not much in it at the moment but is starting to grow and will continue to grow with an increase of users.

There are many additions to the engine that are on the road map such as multi threading and tree physics.
The feature list is constantly evolving with each user request and idea put forth.

Skyline has a custom editor that gives the user of making their own tools for use directly in the editor to develop their games. All the editors are made using the Qt Designer and programmed in lua inside the engine itself.

Open-Source Virtual Reality support is in development.

Shadow editor.
Weapon Class Editor.
Mesh Editor.
Advanced Mesh Editor.
GUI Editor.
Script Editor.
Environment Editor (volumetric clouds and day night cycle, lightening, ocean settings, height fog).
Particle Editor.
Path editor.
Schematic editor.
Navmesh editor.
Material editor.

The documentation is been rewritten and follows a structure like a course.
Introduction to > Level designer with examples > Artists

There is also video tutorials, video examples and video tutorial series been produced.

There are user created demo scenes, examples and more.

Making HUDs and GUIs has never been easier

Full PBR workflow, your not stuck to Secular or Metallic it has both

Can contact the Skyline developers and they will always respond and help as fast as they can.