Warhammer Fantasy is very similar to DnD, but uses different rules. DnD itself is really just a rules set, laid on top of several "official" worlds like Faerun (Forgotten Realms), Greyhawk, Spelljammer, etc, so you could run DnD using the 'lore' of Warhammer Fantasy Battles if you want.I thought D&D and Warhammer shared the same universe for some reason. Like D&D was the past/old world fantasy and Warhammer was the future/sci-fi.(shows how much I know... Though when I think about it, I did collect some of the old fantasy Warhammer with my bro when we were kids)
Having watched the latest movies recently, I'm getting back into Dune lore. Going to pick up some of the later books ASAP.
GURPS is similar, as are several other generic rules sets. Personally, I find rules more tailored to the setting to be more fun, thematic, and interesting. DnD, for example, does not handle firearms well, especially anything modern, and really breaks down in a sci-fi setting IMHO, compared to dedicated sci-fi rpg rules.