There have been a few interesting arguments about dual-n-back games. They have been shown with very solid evidence to improve cognitive performance. They are in

There have been a few interesting arguments about dual-n-back games. They have been shown with very solid evidence to improve cognitive performance. They are interesting in the beginning but get frustrating/difficult very fast, essentially you always play at a frustrating level where you final frequently. It is somewhat exciting but certainly not addicting/motivating in the sense of Civ or other well-developed 'addicting' games. One of the theories on why they are effective (doubting the main interpretation that they train your working memory/cognitive processing) is that the game trains you to endure frustration and at some point also boredom. Dealing with frustration and boredom are actually important success skills - so if there was a way to get the game more engaging there's a good chance that the positive impact would be reduced. tl;dr: issue is still under debate, but it might well be that the need to endure boredom/frustration in at least the dual-n-back games might be a feature (that improves impact) rather than a bug.