RTS games are notoriously difficult (the engine doesn't matter in this case). You have some benefits with C2 because pathfinding is built in, but it's a monumental task. There's seriously a ton that would need made. It makes my RPG look simple. I'm sure someone has done some small tests and such, but I haven't seen one made in C2 to my knowledge. It already has native Spriter support (literally drag the scml/scon files into C2 and voila) and someone is working on a spine plugin, however.