When comparing Gosu vs Twine, the Slant community recommends Twine for most people. In the question“What are the best 2D game engines?” Twine is ranked 38th while Gosu is ranked 50th. The most important reason people chose Twine is:
The basics are very easy to grasp, and you can have a basic story up in minutes.
Specs
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Pros
Pro Lightweight
Gosu is not a game development framework, only a media library that happens to be suited to game development. (Kind of like SDL in the C world.) That means the interface is relatively small.
Pro Mature API, actively maintained and developed
Gosu has been under development since 2001. It is mature and has several toolkits built on top of it to provide additional functionality.

Pro Cross-platform, even mobile, using Ruby
Pro Easy to understand
The basics are very easy to grasp, and you can have a basic story up in minutes.
Pro Free for commercial projects
Twine is based on a GPL licence. You are free to download, modify and publish derivatives - even commercially.
Cons
Con Deploying Ruby apps is a mess
Games built with the Ruby to .exe "compiler" do nothing more than extract your source code and Ruby.exe to %TEMP%, then run it. The code is not really compiled at all. The process for wrapping games as Mac apps is a bit nicer, but you'll need a paid Apple Developer subscription to code sign the app, or users will see a warning/error when running your game.
The only way to really compile Ruby is to use RubyMotion, which does not work on Windows and requires a paid subscription on top of the Apple Developer one.
(This Con is not specific to Gosu. Deploying Ruby code has never been fun.)
Con Limited to interactive fiction
Twine is specialized to decision-based interactive fiction. Under the hood, a Twine game is just a flowchart for page transitions; the only way to add more complex behavior is to code it from scratch in JavaScript.
