When comparing Rainbow vs CRM32Pro SDK, the Slant community recommends Rainbow for most people. In the question“What are the best 2D game engines?” Rainbow is ranked 79th while CRM32Pro SDK is ranked 91st. The most important reason people chose Rainbow is:
Distributed under the MIT License.
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 Great tools included
EditorDPF: resource editor for managing images, tiles, sprites, sounds, etc. of your game
MSTE: tile-based parallax scrolling engine with support to Tiled Qt .TMX files
SetupProject: customized configuration system.

Pro Cross-platform
CRM32Pro works on Windows, Linux and MacOS X.

Pro Open source and free
CRM32Pro is licensed under LGPL license with full access to the source code on the website.
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 Not as beginner friendly
C/C++ skills and general knowledge of SDL and basic game programming is required in order to get all the benefits.
