We’ve pretty much played Settlers of Catan and its expansions to death (though recently we’ve been playing the Settlers of America Trails to Rails variant a bit). However, there looks like there’s a new update coming out that explores the impact of exploitation in the game, giving it a bit of an ethical twist. Could be interesting.
You can read about it at See Oil Springs of Catan explores the tragedy of the commons, while there’s more about the scenario at Tragedy of the commons – Wikipedia, the free encyclopedia.
For another game with an ethical dimension see Terra | Board Game | BoardGameGeek.