ggforce is a package aimed at providing missing functionality to ggplot2 through the extension system introduced with ggplot2 v2.0.0. Broadly speaking ggplot2 has been aimed primarily at explorative data visualization in order to investigate the data at hand, and less at providing utilities for composing custom plots a la D3.js. ggforce is mainly an attempt to address these "shortcoming" (design choices might be a better description). The goal is to provide a repository of geoms, stats, etc. that are as well documented and implemented as the official ones found in ggplot2. The inclusion of any geom, stat, position etc in ggforce is not necessarily a recommendation of their use. ggplot2 has been successful in being opinionated about what functionality should be available. This is good as it insulates the user from making bad decisions when analyzing their data (to a certain degree), but it also makes it difficult to develop novel visualizations using the ggplot2 API. ggforce on the other hand positions itself closer to the "anything goes - the user is responsible for the quality of the output". Be very aware of this responsibility! Bad visualizations lie about, distorts, and obscure the data behind them, both to you and the ones you share your visualizations with.