Only ".map" files are allowed at the moment of Duke format.
More formats to be coded in the feature if required..
Those files below are Usermaps and Mods used on Netplayseeker.
When a player joins your room and doesn't have the Map File on joining one of your rooms or Mod Files, they will get an alert and it will be downloaded automatically to their UserMaps folder (Has now been implemented).
Any maps not found on the web URL a normal File Transfer is planned. (Has now been implemented).
You can upload your own Maps using the "Upload a File" feature above.