ICRPG is my first RPG system that captured me. I tried getting into D&D about 20 years ago, but it didn’t quite happen. So I feel I lack the knowledge of history and context on some of the systems and mechanics, that perhaps is somewhat assumed to be base knowledge. I present the lack of Monsters in ICRPG as an example of this. I don’t really want to buy the official D&D stuff, as I am enjoying the hacky and creative nature of a DIY system, but I do wish for some knowledge on it’s systems.
I don’t know if everyone knows about this already, but I have just found the D&D Systems Reference Document, which is a free, no-fluff version of how the mechanics in D&D works compressed into a tiny 403 page document /s.
Downloadable here:
http://dnd.wizards.com/articles/features/systems-reference-document-srd
Direct Link:
There are great tables on the cost of things, how the spells work, races, on a pure engineering level. The best section is the Monsters, which just simply lists stat blocks without fluff, ripe to be brought over to ICRPG.