When comparing Rainbow vs raylib, the Slant community recommends raylib for most people. In the question“What are the best 2D game engines?” raylib is ranked 36th while Rainbow is ranked 79th. The most important reason people chose raylib is:
Very good for begginers who are looking for game FRAMEWORKS.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Open source
Distributed under the MIT License.
Pro Written in modern C++, is scriptable in Lua
Pro Cross-platform
With support for Android, iOS, Linux, Mac OS X and Windows.
Pro Optional FMOD audio engine
Pro Supports Spine
Pro Physics
Box2D integrated with Lua bindings.
Pro Simple
Very good for begginers who are looking for game FRAMEWORKS.
Pro Support forum
Though it's a small project, it has a forum on the webpage with helpful content available.
Cons
Con Not as feature-rich as other engines
Con Small community
Being fairly new on the scene, there aren't much of a community to speak of.
Con Just coding
Lack of an interface, visual help or auto-debugging could make it difficult to use for a complete beginner.