For Sacred Citadel, there are 4 playable characters which means you can create different kinds of "teams" to play around with. Within each team setup, you can find your best role with each character (and equip weapons/armor and level it to your taste). So if you are playing with two friends, you can keep playing it again and again with different characters in different teams.
But no, you can't have three of the same characters in one team/group because the idea is to support each other in co-op. If your friends are being anal about selecting the same character you want to play, I suggest using the same tactics you used whenever someone picked the Amazon or the Dwarf in Golden Axe II before you could
The story of Sacred Citadel takes place a long period of time after the first two Sacred games, and will act as a prelude to the events in Sacred 3.
You can see it as roughly [S1/Sacred 2====================Sacred Citadel==Sacred 3] for the timeline.
It doesn't show it that well in the cam videos, but the foreground and background are really easy to distinguish when you play it. You also can't walk into the background so it's pretty hard not to know where you can and can't go. There was plenty of skepticism at gamescom from Sacred fans, but a lot of people who gave it a try actually did have fun with it even though it's a completely different genre! Talk is cheap, of course, so once there is a demo or an event where you can play it, I'd say just give Citadel a try and make up your mind based off that.
Speaking of which, if anyone is going to PAX Prime in Seattle this weekend, we're showing Sacred 3 to the public for the first time and we have Sacred Citadel playable at our booth. If you're going and want to say hi, I'll be locked inside our booth for most of the day so it's easiest to hit me up on Twitter at @Sacred_world
and tell me to escape my little booth prison to come talk for a bit
. I'd be happy to!
If you're not at PAX, keep an eye out in the second half of this week and the weekend for Sacred 3 press coverage from gamescom and PAX.