ReadMe for Robocode

Updated 27-Feb-2013 by Flemming N. Larsen

Robocode Home Page:


  1. What is Robocode?
  2. History of Robocode
  3. System Requirements
  4. Getting Started
  5. Robocode API
  6. Robocode Repository
  7. Community
  8. Challenges
  9. Competition
  10. Command Line
  11. Links
  12. Reporting Defects
  13. Feature Requests
  14. Versions
  15. News
  16. How to contribute


Robocode is a programming game where the goal is to code a robot battle tank to compete against other robots in a battle arena. So the name Robocode is a short for "Robot code". The player is the programmer of the robot, who will have no direct influence on the game. Instead, the player must write the AI of the robot telling it how to behave and react on events occurring in the battle arena. Battles are running in real-time and on-screen.

The motto of Robocode is: Build the best, destroy the rest!

Besides being a programming game, Robocode is used for learning how to program, primarily in the Java language, but other languages like C# and Scala are becoming popular as well.

Schools and universities are using Robocode as part of teaching how to program, but also for studying artificial intelligence (AI). The concept of Robocode is easy to understand, and a fun way to learn how to program.

Robocode offers complete development environment, and comes with its own installer, built-in robot editor and Java compiler. Robocode only pre-requires that a JVM (Java Virtual Machine) to exist already on the system where Robocode is going to be installed. Hence, everything a robot developer needs to get started is provided with the main Robocode distribution file (robocode-xxx-setup.jar). Robocode also supports developing robots using external IDEs like e.g. Eclipse, IntelliJ IDEA, NetBeans, Visual Studio etc., which supports the developer much better than the robot editor in Robocode.

The fact that Robocode runs on the Java platform makes it possible to run it on any operating system with Java pre-installed, meaning that it will be able to run on Windows, Linux, Mac OS, but also UNIX and variants of UNIX. Note that Java 6 or newer must be installed on the system before Robocode is able to run. See the System Requirements for more information.

Be aware that many users of Robocode (aka Robocoders) find Robocode to be very fun, but also very addictive. :-)

Robocode comes free of charge and is being developed as a spare-time project where no money is involved. The developers of Robocode are developing on Robocode because they think it is fun, and because they improve themselves as developers this way.

Robocode is an Open Source project, which means that all sources are open to everybody. In addition, Robocode is provided under the terms of EPL (Eclipse Public License).


The Robocode game was originally started by Mathew A. Nelson as a personal endeavor in late 2000 and became a professional one when he brought it to IBM, in the form of an AlphaWorks download, in July 2001.

IBM was interested in Robocode, as they saw an opportunity to promote Robocode as a fun way to get started with learning how to program in Java. IBM wrote lots of articles about Robocode, e.g. like Rock 'em, sock 'em Robocode! from AlphaWorks / developerWorks at IBM, a series of articles like Secrets from the Robocode masters, and "Robocode Rumble / RoboLeague".

The inspiration for creating Robocode came from Robot Battle, a programming game written by Brad Schick in 1992, which should still be alive. Robot Battle was, in turn, inspired by RobotWar, an Apple II+ game from the early 1980s.

The articles from IBM and the Robocode community behind the RoboWiki made Robocode very popular as programming game, and for many years Robocode has been used for education and research at schools and universities all over the world.

In the beginning of 2005, Mathew convinced IBM to release Robocode as Open Source on SourceForge. At this point, the development of Robocode had somewhat stopped. The community around Robocode began to develop their own versions of Robocode with bug fixes and new features, e.g. the ‘Contributions for Open Source Robocode’ and later on the two projects, RobocodeNG and Robocode 2006, by Flemming N. Larsen.

Eventually, Flemming took over the Robocode project at SourceForge as administrator and developer in July 2006 to continue the original Robocode game. The RobocodeNG project was dropped, but Robocode 2006 was merged into the official Robocode version 1.1 containing lots of improvements. Since then, lots of new versions of Robocode have been released with more and more features and contributions from the community.

In May 2007, the RoboRumble client got built into Robocode. RoboRumble is widely used by the Robocode community for creating up-to-date robot ranking lists for the 1-to-1, Melee, Team, and Twin Dual competitions.

Since May 2010 a .NET plugin is provided for Robocode using a .NET / Java bridge, which makes it possible to develop robots for .NET beside developing robots in Java. This part was made by Pavel Savara, who is a major Robocode contributor.


In order to run Robocode, Java 6 Standard Edition (SE) or a newer version of Java must be installed on your system. Both the Java Runtime Environment (JRE) and the Java Developer Kit (JDK) can be used. Note that the JRE does not include the standard Java compiler (javac), but the JDK does. However, Robocode comes with a built-in compiler (ECJ). Hence, it is sufficient running Robocode on the JRE.

Also note that it is important that these environment variables have been set up prior to running Robocode:

You can read more details from here:

If you want to program robots in .NET or control Robocode from a .NET application, you need to install the Robocode .NET API plug-in on top of Robocode. The plug-in is installed by double-clicking the robocode.dotnet-xxx-setup.jar the same way as Robocode itself is installed.


Most documentation about Robocode is provided thru the RoboWiki, which contains the official documentation about Robocode, but which also hosts the community around Robocode. It is highly recommended to read the articles on the RoboWiki for getting started with Robocode. These articles are provided from here:

You should read about the anatomy of a robot, the game physics, scoring etc.

To learn more about developing robots for .NET, these articles are a good starting point:


The Robocode API is provided as HTML pages for both the Java and .NET platform.

The Robocode API actually consists of 3 different APIs.


If you want to try out new robots than the sample robots that come with Robocode, you should visit the Robocode Repository.

Robots are available under the Bots section of the repository.

The Robocode Repository is developed and maintained by David Lynn as a project independently of the Robocode project.


The community around Robocode is using the RoboWiki as communication channel. At the RoboWiki, people share new ideas, code snippets, algorithms, strategies, and lots of other stuff about Robocode. New official documentation from the developers of Robocode will be put at the RoboWiki as well.

On the RoboWiki, these strategies are provided:

The code snippets are also provided on the RoboWiki:


A good way to improve you self as a robot developer is to try out some real challenges. On the RoboWiki, two famous challenges exist for testing/studying a robots movement, targeting, and gun abilities:


If you want to challenge your robot(s) and yourself as robot developer, the RoboRumble@Home is the best way to do it. RoboRumble is the ultimate collaborative effort to have a live, up-to-date ranking of Robocode bots. It uses the power of available Robocoders' computers to distribute the effort of running battles and building the rankings.

RoboRumble is actually 3 different rumbles:

In order to get started with RoboRumble, you should read this page:

Note that the RoboRumble@Home client is built into Robocode and can be started using the batch/shell/command files:

Windows UNIX / Linux Mac OS
RoboRumble roborumble.bat roborumble.command
MeleeRumble meleerumble.bat meleerumble.command
TeamRumble teamrumble.bat teamrumble.command

Two other competitions exists which are:


It is possible to specify options and predefined properties from the command-line when running Robocode. The usage of these can be listed by writing this from a command prompt or shell:

robocode -help

For example, it is possible to:

You can read more details here:


Links relevant to Robocode are provided on the home page of Robocode:

Other links are provided from the RoboWiki - especially for challenges and competitions:

The is also a Wikipedia page available about Robocode, which provides good links to movement and targeting strategies, competitions, and other sites about Robocode:


If you discover a defect (bug) in Robocode you are encouraged to report the issue as soon as you discover it - the sooner the better.

A bug report should be reported on the Bugs page on the SourceForge site for Robocode. Each bug report will be prioritized among other bug reports depending on its impact on the game.

It will be a great help if you describe how to see or which steps to do in order to reproduce the defect. You are very welcome to provide a screen shot, source code or anything else that will show the bug. It is also a very good idea to write which system and version of Robocode and Java you are using.

If you are a registered user at SourceForge (register here) you will be able to add a "monitor" on your bug report. This way you will be able to receive notifications when someone add comments to your report, but will also be able to better track the current status of the bug, e.g. when the bug is fixed and with which version of Robocode the fix is available.

If you are a developer yourself, and have a good idea of how the bug could be fixed, you are more than welcome to do so. By fixing the bug, you will become a contributor of Robocode yourself. You can learn more about how to contribute here. Note that we accept bug fixes under the terms of EPL.


If you got an idea for a new feature or improvement for Robocode, you are very welcome to share your idea by summiting a feature request.

A feature request should be put on the Feature Requests on the SourceForge site for Robocode. Each feature request will be prioritized among other feature requests.

It will be a great help if you describe your idea in detail, and how you think it could be implemented into Robocode. For example, will it be possible to extend an existing feature with your idea?

If you are a registered user at SourceForge (register here) you will be able to add a "monitor" on your request. This way you will be able to receive notifications when someone add comments to your request entry, but will also be able to better track the current status of your entry, e.g. when the feature has been implemented and with which version of Robocode it will be available.

If you are a developer yourself, and have a good idea of how the feature could be implemented, you are more than welcome to do so if the feature is being accepted. By implementing the feature, you will become a contributor of Robocode yourself. You can learn more about how to contribute here. Note that we accept implementations under the terms of EPL.


Robocode is continuously under development, and you should be aware that three different release types exist for Robocode:

15. NEWS

News about Robocode is put on the blog spot for Robocode. Here it is possible subscribe to a RSS feed to receive news about Robocode.

You can also follow Robocode on Twitter and Facebook here:

The RoboWiki can be followed on Twitter as well:


If you want to contribute to Robocode with e.g. a new feature or bug fix, you should read the Developers Guide for building Robocode.

Note that we accept code changes under the terms of EPL.

There exist no or little documentation about the internals of Robocode, and the code base will need to be examined by a contributor in order to get an insight of how Robocode is implemented. Thus, it required a skilled Java developer to figure out how Robocode is put together.

Robocode is divided into several modules. You can read Pavel Savara's blog to get a good overview of Robocode here:

Help for Robocode internals can be provided through the Robocode Developers Discussion Group where you can register yourself, and start up a new topic. This is the best way of getting information and asking about details for the internals in Robocode.

If a contribution is a somewhat small change to involves under 10 files, then the preferred way is to provide the contribution as a patch file that can be applied to the existing Robocode sources. Otherwise, you can be granted a Subversion branch for your work, where you can commit your changes. Later, this branch needs to be merged into the trunk be the administrators of Robocode and tested carefully. Additional work might be done by other Robocode developers to finalize the work.