From the introduction:
Welcome to the second major version of the Game Engine Manual. It¡-s been an interesting road so far Response to the game has been great, much more than I expected. I want to start off by thanking everyone who wrote to me about the game, and thank them again for their kind words.
In the two years since GEM was first put together, I've been making a number of small and subtle changes. There've been some requests that were put in, and some streamlining of things that were a bit clunky before. Most of these things were subtle and minor, but they started to build up. After so long, it became obvious that a slight revamp of the
system was needed.
[...]
The Game Engine Manual is, and isn't, a complete role-playing game. In this book are the basic rules for a role-playing system, including character generation, training, combat, and improving characters. Don't worry if these terms aren't familiar they soon will be.