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About Java4K

What is Java4K?

The Java4K competition is a game programmer competition. The goal of the competition is to create the best game possible in Java. So what's the catch? There is a 4KB limit! That means maximum of 4096 bytes! You can read the competition rules for more details on this.

But why 4KB, and not 8KB or 6KB? The answer to that question is simple. 4KB is the smallest unit of file possible on most operating systems, if you create a file that contains only one character (or one byte) it takes up 4KB on the disk. Along with that fact, mere 4KB seem to be just the right size, anything more and it would matter if you had a good artist doing your graphics or if you had 10x more time than the other developers. 4KB seems to be limitating enough, in other words it's a perfect fit for 1 person to work on, it wouldn't be practical for a large team, consisting of programmers and artists, to work on a 4KB game, it makes it more fair.

If you're interested in creating a game and submitting it into the Java4K competition then we recommend you visit the Java 4K Wiki Page, which should help you understand the fundamentals, and the forums, where most of the 4K developers hang out at. You'll also need to create an account on this site to submit your game.

Short History

This all started back in 2002 when Lloyd Lee (aka mlk) hosted the first contest (2002-2003), which was hosted at JGO ( forums and also Sun Microsystem Java forums. A year later the contest was held again, but this time Matt Campbell (aka woogley) managing it. He put up the site, where the contest was hosted three times in a row; 2004-2005, 2005-2006 and 2006-2007. Once it became clear that Matt was not going to manage the 2007-2008 competition, then website was kick-started by Arni Arent (aka appel) and Joakim Johnsson (aka jojoh) in December 2008.

Dates & Submission Period

The Java4k 2008 Submission period is over, results will appear on this site before March 14th.

The Java4K 2008 submission period spans from December 1st 2007 and ends February 29th 2008. Results of the competition will be displayed on this site shortly there after.

Usually the submission period is 3 months, spanning december and january and february of the next year.

Competition Rules

The rules are as follows:

  1. The final game package (byte code + resources) must be below or equal to 4096 bytes
  2. Must be a playable game (cannot be a pointless animation)
  3. Must be pure Java (no JNI)
  4. Must be self-contained- no external resources (e.g. loading an image from a website)
  5. No Pack200
  6. No external libraries may be used - you must use the libraries that come with the "public" version of the JRE
  7. No soundbanks may be used because they are not a default part of the "public" JRE. You will have to create your sounds at runtime rather than use MIDIs.
  8. The game must be startable using Java Webstart. (see below for more details)
  9. The target JRE is 1.5 (Java 5) or lower
  10. Must not be identical to a game submitted into previous 4k competitions.

Some extra notes about Java Webstart:

The administration reserves the right to reject games that do not follow the spirit of the 4K competition, e.g. try to cheat or bypass competition rules.


There will be two types of judging, a judging panel consisting of a few judges (yet to be picked and defined) and a community vote, where everyone can participate in voting the best community game.

The judging panel will consist of both programmers and non-skilled-humans, and they will choose the winning games in 3 categories:

So, in short, there are 4 categories:

Currently there is no plan to give prizes.

Judging Panel

The judges for the Java4K 2008 competition are as follows:

Getting Started

If you're interested in making a 4K game but don't know how, check out these links:

Links Related to 4K programming


If you have any questions you can send them to user "appel" at (@) domain "".