Bulletin Board System (BBS) Levels is the game's central hub for browsing and playing user-created levels. Because the content is user-created, it will have varying degrees of quality, length, and polish. The content is mostly created by users, and are categorise into 3 categories. The categories are as follow: Finished Levels, Work in Progress/ Experimental and Models & Objects.
Finished Levels are levels which are completeable, polished and unlikely to be updated (or not until a major version in the case of WIPs).
WIPs/ Experimental are levels which are experiments in gameplay, quirky levels that don't have an end, experiments in scene design, and ongoing projects that would like feedback.
Models are for posting models that other people can grab to use in their levels. You can post levels here too, in order to conveniently showcase the objects. Eventually this forum will also house dynamic objects like monsters when the editor supports them.
Currently, there is no way to rate levels, but the feature will be added in an upcoming update.