When comparing Moai SDK vs Ren'Py, the Slant community recommends Moai SDK for most people. In the question“What are the best 2D game engines?” Moai SDK is ranked 19th while Ren'Py is ranked 39th. The most important reason people chose Moai SDK is:
Because it uses Lua + C++.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Fast
Because it uses Lua + C++.
Pro Gives you total control
You can use your own custom shaders and extend the language with C++. MOAI doesn't give you everything, instead it gives you the tools you need to develop any game you want.
Pro Full source code is available
So it is extendable with C++
Pro Easy-to-use particle engine
Uses a limited subset of Lua
Pro Uses Lua, with LuaJIT where possible
Pro Is used by many pro developers
Moai SDK is used by popular developers including Double Fine for their mobile game, Middle Manager of Justice, and for their Kickstarter hit, Broken Age(formerly, Double Fine Adventure.) It was also used to create the popular mobile game Bubble Ball 2.
This proves that this engine can be used to make fully-featured and fun games.
Pro API interfaces
Has options for development like Hanappe and Rapanui, providing a different way to interact with the engine.
Pro Helpful community
The Moai SDK Forum is active and users will go to great extents to answer queries, post code snippets, beta test, and even purchase and give feedback on each others' games.
Pro Helpful and detailed documentation
Although the Moai SDK is very advanced and uses complicated features, the documentation wiki thoroughly and clearly explains how to use these features, such as the Moai Cloud(a service that provides web services for your game), and multiple ways to build from source.
Pro Cross-platform
Available on Windows, Linux, OSX, iOS and Android.
Pro Active and friendly community
Pro Reasonably good at creating puzzle and point-and-click games
Cons
Con Not for beginning developers
The Moai SDK has very advanced features which allow it to create powerful games. A drawback from this is that it is not very suitable for beginners.
Con Not necessarily tested or stable
Con Scarce documentation
Since it is a minimalist framework there is not that much documentation, but if you are used to reading API references and source code you are good to go!
Con Development has ceased
The last update was over a year ago. Users should not expect things to still work on future OS versions unless they're ready to fix them yourself.
Con Not for every genre
While technically capable of creating 2D games in any genre, Ren'Py excels in creating visual novels and has a reasonable feature set for creating puzzle and point-and-click games. Other genres are best tackled by other engines.
Con Outdated Documentation and official built-in tutorials
Unfortunately, you will have to hunt relevant info on how Ren'py script works. The Ren'Py dev has the working tutorials on his Patreon, other than that you might as well just code in Python.