Obviously, the random map generation is the key. I know the map generator from the original game is not the greatest, but will use that as the starting point. The re-implementation may also be the ending point as the maps from DR were good-enough so reworking the code will be done near the end of development if time allows. As time will probably not allow, expect just a tweaked version of the Dungeon Romp maps.
Items will be the big thing that I will try to focus randomness on. The types of items available will vary from game to game as well as (within realistic ranges) the properties of those items. One game may have swords being the best weapon to have, while the next one battle-axes may have superior models and stats. Magic will have both beneficial and detrimental variants with a possibility of some spells being a mix of both (think of a spell that causes massive damage on an opponent but at the same time reduces the melee skill of the player for a number of turns).
Finally, I would like to have more varieties of monsters. Both in the type of monsters and how powerful those monsters are. In one game you may face level-1 goblins which are easy to defeat, while the next time the goblins will be generated at level 5 stats so the player has to re-familiarize him/herself with the monsters in every play.
That is my plans for my first-ever 7DRT. If nothing unexpected happens, I should be able to put in 50-60 hours durring the next 168 hours available to me so have a good shot of having a finished game.