Dragonshard is hands down the most innovative RTS on the market today, despite being created more than a decade ago.

Set in the Dungeons & Dragons world of Eberron, there were 4 factions, 3 of which has complete playable campaigns.

The story is set in a mysterious place called the Ring of Storms.  A location that was added to the Eberron world as a result of this game.  Here, shrouded by a ring of perpetual storms lies a great treasure and an even greater mystery.

Play as The Order (Humans, Elves, Dwarves, Etc.), The Lizardfolk (a combined army of intelligent, cold-blooded creatures), or the Umbragen (a shadowy race of dark elves unlike the others on Eberron).

Double layered battlemaps:  Each mission has 2 maps.  Above ground map and the below ground map.  The above ground map is where your build yor strongholds and train your fighting forces.  Below ground lies an ancient collapsed city that holds buried treasure and hordes of monsters.

Above Ground:

Players create their stronghold using an innovative grid system where buildings effect each other depending on their proximity to one another.  From there, they train captains, Heroes, Juggernauts to do their bidding.

Captains command a squad of soldiers who are weak by themselves but are very effective as a group.

Heroes are tougher than captain, have special powers, can level up with experience, and can hold magical items and other inventory.

Juggernauts are the lords of the upper battlefield.  They take a long time to create but their power and abilities are necessary for the end game.

The Above ground map was filled with wonderful detail and interesting tech features like swaying grass, trees, and 'hyper-terrain'.  Hyper-terrain was a layer of terrain that sat on top of the ground layer.  Often indicating sand, mud, or snow, the ground would deform in real time and the soldiers moved over it and would leave tracks.  When it rained or snowed, the the tracks would be smoothed out.  This turned out to be a strong tactical consideration when you traveled overland.

The building grid system, the squad system, hyper-terrain, realtime wind modelling and moving vegetation are just some of the above ground features which have yet to be duplicated in another RTS.

Below Ground:

Under every map, lies another.  The ruins of a sunken city.  It is filled with traps, monsters, and treasure.  Players can send captains and heroes down into the depths to recover treasure and help the war effort.  Ignore the underground and your opponent will gain the upper hand.  Captains are weaker down in the depths since they don't take their squad with them and Juggernauts cannot fit into the entrances to the city.  Every captain has a role similar to a character class in D&D and those roles shine in the depths.  Encountering lots of traps?  Better bring your Rogue captain.

The game played like an RTS on the surface world and played like an action D&D game underground.  This led to the creation of some of the most unique single player missions ever seen in RTS games.

Together:

We used some really hot proprietary technology to allow us two maps operating simultaneously.  With a single keystroke or a click of the appropriate minimap, you would instantaneously be taken to the other map with no load time.  This was unheard of and still never attempted.  It was the first RTS to require strategic thinking on one map and tactical thinking on another.   

Innovative in ever way, Dragonshard is a great representation of what Liquid is capable of when properly funded, and has remained in the top 20 in the RTS category on Good Old Games gog.com since it was listed there years ago.