When comparing Gosu vs Blacksmith 2D, the Slant community recommends Blacksmith 2D for most people. In the question“What are the best 2D game engines?” Blacksmith 2D is ranked 48th while Gosu is ranked 50th. The most important reason people chose Blacksmith 2D is:
Automatically detects changes and updates bitmap cache. Allows to gain even more performance on heavy scenes and runs smoothly on old devices.
Specs
Ranked in these QuestionsQuestion Ranking
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 Cache as bitmap
Automatically detects changes and updates bitmap cache. Allows to gain even more performance on heavy scenes and runs smoothly on old devices.
Pro Most valuable when size matters
All engine code is written in ES6, fully GCC typed, allowing to eliminate all dead code from your app.
Pro Advanced scene graph and rendering pipeline
Dirty flag tracks scene changes and avoids unnecessary calculations and context calls. If no changes were made to the scene since last frame, no rendering will be done. Battery efficient.
Pro Good performance
According to the tests on the Github page, the performance is better than in Phaser!
Pro Good and clear source code
The source code is well commented and easy to understand.
Pro Super small build size
Super small build size through dead code elimination. The best for playable ads and Facebook Instant Games.
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 Small community
The project is young, so the community is extremely small.