This might become less useful with the release of the development tools, but it remains an easy way to tweak difficulty settings since that feature wasn't included in the final game. In fact, some difficulty settings were implemented but never used, and you can tweak them all here. For cheaters, you can also set item prices, maximums, and (with some restrictions) starting equipment. Trust me: you haven't lived until you've given yourself tens of thousands of oil flasks and fire arrows. You can find the older version (which works only with the original gamesys, not modified ones like those in the newer versions of the minimalist mod) here (requires the .Net Framework).
Versions 2.0 and up require the Java Runtime Environment (JRE) version 1.4 or later from sun.com, such as the J2SE (standard edition) 5.0.
I've created a modified version of the original gamesys. It eliminates starting equipment woes. Be sure to use the OrigPlus.ver file with the tweaker!