Mysterium is a cross between Dixit and Clue. It's clue cards, like Dixit, are beautiful and if need be you can play with easier rules when the 11yo join. It's largely co-op.
Revolution is a bluffing game. You need to be at least 5 people to play though.
Betrayal at the House on the Hill is a nice, long horror game with certain RPG elements. It just requires three people, but it might be a bit much for the 11yos (in terms of game play, not because it's scary). It's completely co-op until at a random point in the game it's revealed that there's a traitor in the group (determined by a certain conditions determined in turn by what triggered the reveal, so you really don't know who it is until the reveal). Then it's a 1 vs. everyone else.
Before 2020 I would have recommended Pandemic, but since the real-life pandemic... Sensibilities vary, so know your audience, I guess. It's a co-op game where you battle against 4 diseases before they spread too far in the world.
Re: Board or Card Games
Revolution is a bluffing game. You need to be at least 5 people to play though.
Betrayal at the House on the Hill is a nice, long horror game with certain RPG elements. It just requires three people, but it might be a bit much for the 11yos (in terms of game play, not because it's scary). It's completely co-op until at a random point in the game it's revealed that there's a traitor in the group (determined by a certain conditions determined in turn by what triggered the reveal, so you really don't know who it is until the reveal). Then it's a 1 vs. everyone else.
Before 2020 I would have recommended Pandemic, but since the real-life pandemic... Sensibilities vary, so know your audience, I guess. It's a co-op game where you battle against 4 diseases before they spread too far in the world.