• Internet Explorer is changing my jarfile to a zipfile
  • Double-clicking jarfile opens a folder
  • Double-clicking jarfile asks what program to use
  • Program exits when starting a server
  • Program hangs/exits when connecting to server
  • Game crashes near end
  • Game crashes in other circumstances
  • Don't understand how to play
  • Other problems

    Download Problems

    Problem: Internet Explorer is changing my jarfile to a zipfile or compressed file folder!

    Solution: This is due to misbehavior of certain versions of Internet Explorer. Basically, what's happening is that our web-server sends the jarfile with MIME-type "application/octet-stream", which the browser is allowed to interpret however it wants. Internet Explorer is smart enough to know that a jarfile looks much like a zip archive, and thinks it's being helpful by converting it, but is too stupid to know that it should actually just leave it alone.

    There are two solutions to this problem.

    1: Use a different browser. If you download the program with Firefox, you won't have this problem.

    2: Change the file's type after it is downloaded, which may be easy or hard, depending.

    If you have "hide file extensions" turned off, this is easy: just change the file's name from to blahblah.jar.

    If the file's name is shown as just "blahblah", not "", you have to unhide the file extensions first. First, open up "My Computer" and navigate to the directory where you saved the jarfile. Once you're in that folder, go to the "Tools" menu and click "Folder Types". On the "View" tab, turn the option "Hide extensions for known file types" OFF. Click "Apply". Now you can edit the filename extension and change it from .zip to .jar.

    Problems Starting the Game

    Problem: When I double-click the jarfile, it doesn't start the game; instead, it opens up some folder with a bunch of files in it.

    Solution: There are two possiblities here. The first is that the file extension on your jarfile has been changed from .jar to .zip, in which case see the answer in the "download problems" section.

    The second possibility is that the .jar file association has been stolen by some other program. (Lots of zip programs do this.) The solution is to reassociate the .jar extension with javaw.exe. If you right-click on the jarfile and click "open with", you can click "choose program", select javaw.exe, and check the "always open with this program" checkbox to reassociate jarfiles with java.

    Reinstalling java should also fix the file associations.

    Problem: When I double-click the jarfile, it asks me what program to open it with.

    Solution: You need to install java to play the game. Installing java is pretty painless. Just follow this link to Sun's website, click on "Download J2SE JRE", and follow the instructions.

    (Versions later than 1.4.2 should also work. The JRE is the "runtime environment", required to run java programs. The SDK is the much larger "developer's kit", required to create java programs; it includes the JRE.)

    Problem: When I try to start the server to host a game, the program exits or hangs instead of showing the server-running window.

    Solution: This generally is caused by the game being unable to connect to the DD website (, where the master list of games lives. It could be that the program doesn't have permission to access the network, or that the website is down, but most often this happens because your computer is having problems with its net connection. Make sure that you can access the internet and the DD website and try again.

    Problem: When I try to connect to a game server, the program just hangs, or it just shuts down.

    Solution: This probably means that your client's connection to the server is being blocked by a firewall.

    In order to play the game, your client has to be able to talk to the server that is hosting the game. That means that whatever machine the server is running on has to be allowed to accept incoming connections from the other copies of the game.

    The game tries to connect on port 9999. If you have control of the server's firewall and can open up that port, everything should work fine. If you can't or don't know how to do that, you'll probably have to involve your sysadmin to get the port open.

    Note that in the current version of the game, the startup window disappears after you click "Start", but the game window doesn't appear until all players have joined the game. Only worry about problems with the firewall if you're certain the game is exiting instead of allowing you to join the game.

    Problems Running the Game

    Problem: We got near the end of the game, and then the game crashed.

    Solution: The game can use up a lot of memory. Unfortunately, when java runs out of memory, the game just crashes. Note that just because you ran out of memory once doesn't mean you always will; it depends on what happens in the game. It's more likely for a server to run out of memory then a machine running just a client. Robots use more memory than regular players; if your machine is low on memory, the most likely case for running out of memory is if you're playing a game with three robots and one human player.

    You can limit the amount of memory that a java program uses by running it from the command line with the -Xmx flag. This will cause it to slow down a bunch when it hits the memory limits, but it won't crash.

    java -Xms64m -Xmx128m -jar program.jar tells java to run program.jar with a starting memory size of 64 MB and a maximum of 128 MB.

    Problem: The game crashed, but I don't think it ran out of memory.

    Solution: No game is perfect, and it's distinctly possible that you have found a bug. Sorry about that. If you can reproduce the problem, we would greatly appreciate a report so we can fix it. See the Reporting Bugs page.

    Problem: I'm confused about how to play the game.

    Solution: Read the walkthrough. It's a pretty thorough tutorial that explains all aspects of gameplay.

    Problem: I have some other problem not described here.

    Solution: Send us email! The more problems we hear about, the better we can make the game. Note that many of the problems described here are Windows-specific and are unlikely to occur on a Mac or Linux system, but we are happy to hear from you regardless of OS.