Jazz Jackrabbit 2 Plus (JJ2+) adds countless features and bug fixes to both Single Player and Multiplayer gameplay within JJ2, and is used almost universally by most serious players. It has much better network code than the original game, adding console commands to online games, fixing most major game-crashing errors and connection problems, allowing permitted clients to log in as "remote administrators" in someone else's server and control the gameplay, and adding several new multiplayer gamemodes. It additionally fixes or enhances many of the events in the game, and allows level designers far more power than in regular JJ2 through the addition of an easy-to-use scripting language. JJ2+ takes everything great about JJ2 and adds so much more on top of it; it is truly a must-download.
The 5.# family of JJ2+ releases have introduced AngelScript functions to use more than eight layers, and more than one tileset, in a single level. This screenshot shows a level combining the Labrat, Inferno, and Winterland Wonder (https://www.jazz2online.com/downloads/1403/-/) tilesets under a single custom palette. Multiple translucent background layers are lightened or darkened to show their respective distances from the camera, and a full sheet of water is drawn in the background as a non-interactive element.