I'm a huge 40k lover, these are the only ones I am familiar with though I know alot about the lore in general. I could get the books for the others, I DM a few Deathwatch games for my friends, and we recently brought in some Dark Heresy characters for a campaign, but I would like to play a game where I don't DM. So, to recap, I know Deathwatch best, some Dark Heresy, but can grab the core rulebooks for any of them fairly easily.