Recs.
Updated
Orx is an open source 2D-oriented, data-driven, portable game engine focused primarily on ease of use and powerful features. It is written in C.
SpecsUpdate
Pros
Pro Custom shader support
GLSL code can be added straight into data configuration files and can be applied to any texture: background or objects whivh allows for some amazing effects. All GLSL versions are supported, again by providing the shader language version in your configuration file.
Parameters are supported and values over time for shader animation.
Pro Good animation engine
Includes a chaining graph & custom animation events for synchronization.
Pro Excellent results on performance benchmark
Rated the fastest engine in the OpenFL’s BunnyMark since October 2015.
Cons
Con Feature discovery and explanation could be better
Some features are not well explained / highlighted: for example, unless you use the interactive project initialization, you have to go over the tutorials and examples in the wiki to learn that there is an optional C++ layer, Scroll, developed on top of the C API. Similarly, some major information are missing from the website, wiki and Doxygen documention, and are left for the users to discover in source headers and INI template files, or by searching the forum (e.g. the 0,0 coordinate being the center of the screen and not top left, the list of all Orx scalar types and their use, etc).