When comparing Rainbow vs TIC-80, the Slant community recommends TIC-80 for most people. In the question“What are the best 2D game engines?” TIC-80 is ranked 49th while Rainbow is ranked 79th. The most important reason people chose TIC-80 is:
The app contains tools for coding, sprite editing, map editing, sfx and music editing.
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 All tools in one place
The app contains tools for coding, sprite editing, map editing, sfx and music editing.
Pro Free
Free version already includes most features but a paid version is available.
Pro Retro-styled and restricted environment
Pixelated Software with a good retro style.
Pro Many Scripting languages' supported
Use awesome scripting languages like: Lua, Wren, Moonscript, JS, Ruby, etc.
Pro Export
Exports easily to Windows, Windows-XP, mac, Linux and HTML.
Pro Noob underdog
You can imagine this engine Shiva Lua scripting language making 2d side scrolling Megaman style games a Bandai trademark.
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.