J2O now has new, more detailed preview images for levels in the downloads section. Choose any download, right back to the very first, and click a level filename under the “File contents” header. You’ll now see an even more detailed preview image than before which includes object sprites, textured backgrounds (where applicable), and even some JJ2+ features like custom palettes, edited tile images, extra tilesets, and extra layers.
J2O’s level preview support originated in 2009, but this update takes it a step further by including sprites like in BlurredD’s 2006 suggestion.
Did you know?
Some people think that you should provide the passwords of your levels in the readme file. That way people who get the level when a server is run won't be able to rip your levels, but if someone decides to add your level to a pack(like Zeal Alpha), they will be able to edit it.