powergod: This is a better explanation for the ones that still are without clues:
Driftland: The Magic Revival -
Is the MAIN/FULL game, it has 4 main campaigns with a story, and, as a bonus
contains already the maps included in
Nomads of Driftland. It
doesn't and can't include the maps present in the DLC
Nomads of Driftlands: The Forgotten Passage.
Nomads of Driftland (that is FREE) - Is a standalone game that only contains a collection of maps,
the same maps also present in
Driftland: The Magic Revival. It doesn't contain a campaign or a full game, it's just a collection of maps.
Nomads of Driftland: The Forgotten Passage (DLC) - Is still just a collection of maps, so no campaign. The maps contained in this DLC
are not present in
Driftland: The Magic Revival, and
can be added only to
Nomads of Driftland. These additional maps can't be added to the main game.
Nomads of Driftland was released as a standalone game for 2 main reasons, first because it was a prototype of a different gameplay from the main game (but never became a full game), and second because releasing it for free they could use these maps as a kind of DEMO and Advertise the main game.
They made the DLC with more maps because they received approvation for this kind of gameplay.
Well, that's what makes it a complete mess.. there's also a free demo version of the main game as well.
I thought I saw another DLC as well, but the mess already had me confused, so maybe not.