Gameplay, what else?
While the bottom line has a familiar ring to it, Cavedog assures us that this won't be just TA with a Spice Girls makeover. By going with a mythological, medieval-esque storyline, Cavedog can infuse a lot of storytelling elements that was somewhat lacking in the original. Along the same lines, Cavedog will use a lot of character development to advance the plot and bring some personality into the game.
The most notable new feature is the inclusion of four races, or factions as they may be, each with its own unique set of units, strengths, and weaknesses. Unlike TA, where 80% of the units between the Arm and the Core were alike, you'll be hard-pressed to find similarities between any of the four factions.
The Earth faction, named Aramon, is set heavily on the ground, making use of the standard medieval footmen and cavalry combination and also an extensive use of gunpowder. The water faction, Veruna, will obviously have a strong water combat background, controlling the seas easily with their far superior naval firepower. On the flip side, there's the Taros Fire faction, which is generally regarded as the most evil of the sides. By calling forth minions of the undead such as mummies, they make use of all their evil and supernatural powers, most notably their destructive magic.
And last but certainly not least, we have the air faction, named Zhon, whose strength obviously lies in its air superiority. But don't underestimate their knowledge of magic, as they too are supernatural, living creatures with an incredibly innate control of those forces. These attributes don't limit you to what kind of terrain or maps you can play on, though common sense would have it that you'd probably pick a faction that is strongest for each particular map. (i.e. water faction for island maps)
Team play factors are enhanced by the inclusion of shared vision and shared resources. Cavedog will also be including more types of multiplayer games - They realize that most people are playing the game for its multiplayer capability, so great care and attention will be paid to network code and TAK's usability on Boneyards, which is Cavedog's online matchmaking service.