Dungeon Crawler has been 100% rewritten in the Java 2 Platform Standard Edition 5.0. If your computer system has the 5.0 JDK (development kit) or JRE (runtime environment) already successfully loaded, Dungeon Crawler will work for you. If you need to know more before you install, check out the supported system configurations at Sun:

http://java.sun.com/j2se/1.5.0/system-configurations.html

Then, if your system can handle the JRE (as it almost certainly can), you can download the necessary installation package at

http://java.sun.com/j2se/1.5.0/download.jsp

Once you have the JRE or JDK installed, head on over to How to Buy Dungeon Crawler and you're ready to start Crawling!