Macromedia Shockwave Multiuser Server (SMUS) is a server application specifically designed for use with the Multiuser Xtra in Shockwave sites and applications. It forms the backbone of some prominent online Shockwave games.

"Features":

• Supports Macromedia's Multiuser Server (MUS) Protocol over TCP and UDP (This is a proprietary protocol developed by Macromedia for use in programs and web applications generated by Macromedia Director)
  
• Supports the seamless transfer of Lingo objects
• Supports server-side scripting in Lingo
  

After version 3, Macromedia discontinued support of the software in favor of the Flash Communication Server, which does not support any of the above features.