This is the 4th edition of Games Workshop very popular tabletop miniature game. The rulebook is mainly a revamped version of the 3rd edition with various rule simplifications throughout. Overall, the mechanics of the game have stayed the same. Rich in background this book offers all kinds of modelling tips, terrrain building and painting guide.
From the back of the rulebook:
" Warhammer 40,000 is a tabletop game for two or more players where you command the forces of the Imperium or one of its many enemies. This book provides you with all the rules you need to play, and guides you through collecting and painting your own army of Citadel miniatures."
- Warhammer 40,000 (fourth edition)