Brutal Legend. God, a thousand times Brutal Legend. It's an RTS like no other - it has the base setup and unit creation of most RTS games, but removes the micromanagement and fiddly, and ultimately pointless, base building.
Instead, the player is a unit themself - the most versatile unit in the game, who can jump into battle, kill stuff, then fly away. On top of that there's the solos - incredibly varied special attacks and abilities which range from melting the faces of nearby enemies, to chaining an anvil to the opponent's leg, to summoning wild animals, to changing the weather to your faction's advantage, to dropping a flaming zeppelin on the map.
And on top of THAT, there's the double teams: not only can you attack alongside your army, you can attack WITH them, with the ability to do a team-up attack with any unit you make that's more powerful than either of you could do alone. These range from simply controlling a more powerful version of the attack, to doing a completely different, and usually decimating, attack.
But because everyone went in expecting heavy metal God of War, they didn't bother learning the intricacies of the battle system. And most people were apparently unable to wrap their heads around the idea of a game with aspects from multiple genres, so their reaction to the stage battles was to sit in the air doing nothing, expecting to win just by ordering their troops around, without ever actually killing anything themself, and never performing a single solo or double team.
If EA had been less scared of marketing this game as what it is, I think it really could have been a big hit.