Not that I'd want to actually game in the Dreamlands per se. That can be done, of course. There's a Call of Cthulhu scenario/setting that explores the Dreamlands. But I'd rather just use the map and a few of the details of the Dreamlands as a setting, and then play it straight as a secondary world fantasy setting, rather than using it as it really is meant to be.
How would I do this, if so?
1st: There's really only one PC race; human. It's not possible to play one of the almost-men of Leng, or a zoog, or a moon-beast, or one of the lunar fish people of Ib or whatever. Only human.
2nd: I'd look to the primary sources (or perhaps secondary sources) of the Dreamlands for inspiration, but not force myself to be completely stuck into the interpretation thereof. Ghouls and ghasts, for example, might be like they are in D&D, or how they are in Dream-Quest, or some other interpretation that differs even more.
3rd: Might have to whip up a little bestiary. Zoogs, gugs, ghouls, ghasts, night-gaunts, shantak birds, moon-beasts, and more all make notable appearances.
4th: The Great Ones, or gods of the Dreamlands, are only vaguely referred to, really, in spite of their prominent "off stage" roles in a few stories.
5th: Magic seems relatively subtle. I don't see any role for clerics, although the more arcane magic-users aren't necessarily out of place.
6th: I'd almost certainly use an m20 variant anyway, although I don't know that I'd use the same one that I use for DARK•HERITAGE. Maybe a more "classic" m20 variant is called for; "Purest Essence" without clerics and a few minor house-rules (like Heroism Points, fer instance, to counter a bit the lack of healers.)
7th: Lovecraft himself never wrote any action-oriented stories of any kind. Randolph Carter is not an action star, and he's a bit questionable in his choice of allies and actions. I'd rather borrow a bit of Robert E. Howard's tone here, and make it a bit more straight-forward in some ways, while still retaining the sense of dark fantasy sword & sorcery as much as possible.
8th: Not all Dreamlands stories were by Lovecraft. Gary Myers wrote a long set of them, collected in the book Country of the Worm. Brian Lumley wrote others. A lot of Lovecraft's own stories are unclear; do they take place in the Dreamlands, or in some kind of semi-mythological past world, not unlike the Hyborian Age? And Lovecraft also generously makes reference to the works here and there to places created by Howard or Clark Ashton Smith, including Valusia, Hyperborea, etc. Some of these would not be unwelcome in my Hybrid Dreamlands campaign.
9th: The map linked in the image is not the DREAMLANDS REMIXED but rather an interpretation of the actual Dreamlands. I wouldn't mind whipping up a DREAMLANDS REMIXED map. I'd love to figure out a way to color hand-drawn maps well and without as much effort as I need to use to do it digitally myself, though.
10th: I'm going to also think about adding some of these locations to my Forbidden Lands area of my setting. I already had, of course, but now that I'm reworking the setting a bit, well, that gives me the opportunity to rework that as well.