if excuses of being meanly a mulitiplayer game is just wrong, there are alot games have a great story/campaign and mulitiplayers, such as starcraft, COH, C&C, warhammer 40k 2 and more. and there are all rts.
also campaign isnt all about story telling, its teach player how to play the game.
and i am not here saying the demigod is bad, cuz it doesnt have a campaign mode. i love the game, its fun and very different from anther games. its just hopeing there is a lot more stuff in it.
you want a great story? read a book or watch a movie.
there are tons of game with great story and gameplay. such as bioshock, freelancer, Psychonauts and more.