I ended up playing it three times. First time I got to 80% but deleted the gamesave when trying to figure out the account system more. After the third time it was starting to get a bit dry, but I had to get to 100% before finishing the game. I love the reward for 100% though.
How about you play it then? You'll get a kick out of it, and maybe if they saw how much fun it is then maybe they'll play too.
I will try it out as I like to play as well. they were just a bit disappointed that they couldn't play together that's all. but they will play it eventually. =)