yeah,yeah actually it was not my sugestion to create a online coop version of such game. In fact, imo multiplayer can wait for second project and also little puzzle games are too small.

we could create a 3rd person adventure/puzzle with a little action and probably with a dark,mysterious story. It doesnt have to be very long, 2-3 hours playtime is ok imo. Downside of such game is that we need good voice acting and musics, and alot of models/levels of same consistent art style. because of that this could also be hard for such group.

the game we are creating should be focusing on gameplay and game mechanics imo, this is what our group can do best. We can follow a easier to create art style.

or

we can go for arcade with things like online highscores and leveleditor etc.(Aaaa! of Dejobaan was a very successfull indie-arcade game ) This could sace us from thinking about a great story,scripting the story, voice acting, too much level design fitting the story etc.

IF you think about it the game should be completed in 6-8 months at max. and none of the group members are doing this as a full time job.