This is not the first Warhammer 40K rulebook nor the last but it is handy. I had played the much older Rogue Trader rulebook at some point. I do have some Orks and a handful of Necron skulking about so this seems a likely candidate for play. Then, I also have some Space Squats and some compatible Russian figures.

Teleport back to the 1980s when Games Workshop was refining its vision of Warhammer and that is when Rogue Trader made its appearance. With a heavy emphasis on background detail, the rules seem more like Warhammer with an SF veneer, psionics replace magic, squats replace dwarves, and orks are still orcs. There are extensive rules for such familiar things as robots, tyranids and genestealers but there are also oddities like Slann and Jokaero, bouncers and Psychneuin. An interesting book especially compared to what the whole thing has become.

From the days of Rogue Trader, this pleasant little book was apparently just the first of a million such books providing army lists and scenarios for the futuristic Warhammer world.