Here's what Wikipedia has to say about demakes (fairly long so I put it in spoiler tags):
Spoiler "Demakes"
Demakes allow amateur video game designers to implement the concept and feel of a complex, high-budget, professionally made video game, in a simpler form–something that would not otherwise be within their capabilities. Popular demakes include Portal's Flash version; Rockman 7 Fc and Rockman 8 Fc, NES-styled demakes of Mega Man 7 and 8; Gang Garrison 2, a pixelated demake of Team Fortress 2; and Halo 2600, an Atari 2600 style demake of Microsoft's Halo series.[1] For much of the 1990s in China and Hong Kong, black market "demakes" of popular contemporary hits for the PlayStation such as Final Fantasy VII and other "next-generation" systems were often made for the NES (and even sometimes porting SNES games to the NES) — the system that many Chinese continued to own and purchase because of its comparative cheapness. Some commercial demakes exist- the most notable being some entries in the Tony Hawks series. These were designed for the most capable platforms at the time of their release and so graphics and code had to be removed in order to be ported to a console with lower capabilities. The most infamous example is Tony Hawks Pro Skater 4 for the PS1, a game where certain graphics had to be removed to the point where the graphics frequently clip, the game runs too slow to make certain jumps that were possible in the PS2 version, and the level backgrounds are dull, some with the 'fog' typical to the format. A more recent example would be the versions of Project 8 and Proving Ground on PS2- using separate levels instead of the free-roaming world available on the PS3 version.
From what I gather a "demake" is a special kind of remake. You know how often you have modern remakes of old games? Well, a demake is the other way around (sort of). It's an "old" remake of a modern game.
Edit: I voted for isometric and turn based. Considering Bethesda remade Fallout as a first person real time game (like Oblivion), it would be only appropriate that a demake of Oblivion is an isometric turn based game (like Fallout 1 & 2).
And considering the poll, right now only 2 people voted that they are interested in a demake and i'm one of them so at least 50% of the people who are interested in the project have voted for an isometric turn based RPG.