The Architecture of Open Source Applications

http://www.aosabook.org/en/index.html

Hey, at least it's free.

>>5
First of all, "advances_to=Elvish Captain,Elvish Hero" is wrong. it should be the other way with "advances_from". So you can add upgrades, without changing base units.

Ideally you should have something like
prototype=Fighter, race=elf, hitpoints=33, damage=5
All else (including alighnment) should be merged from prototype and race. Image files may come from the same