nBack+

nBack is a game designed to improve working memory and fluid intelligence. nBack is a game where the user is required to remember a sequence of values and to determine whether element m is a match to element m-n. For example, if the app calls "A", then "B" and finally "A", this would be a match in 2-back as the second "A" matches the "A" called two prior. nBack comes with standard n-back functionality with some extra customization. You can play on a grid varying from 1x1 to 6x6. You can select between single, dual or tri n-back variants. And, of course, you can vary the n to difficulty. There are also a few other customizations.