Please note that this game is not easy because it is not easy to push human limits for improving oneself. It uses scientifically proven way of improving your working memory and helps you solve problems faster. It's also fun but not in the way you would expect. Reaching new levels in the game is incredibly satisfying. An optional premium upgrade is available through a one-time in-app purchase that will remove ads and enable Google Play Games cloud synchronisation across multiple devices. To get bugs fixed as fast as possible, please use the app's customer service feature. The more (and precise) information you provide for reproducing the bug, the faster it will be fixed. WHAT IS DUAL N-BACK Dual N-Back exercise has been shown to improve working memory and fluid intelligence. Fluid intelligence refers to the ability to reason and to solve new problems independently of previously acquired knowledge. The idea is to keep track of two individual things while playing: flashing square's positions and letter sounds. FEATURES - Simple but challenging gameplay - Graphical statistics with daily progress and trend line - Helpful gameplay animations and tips explaining all you need to know about Dual N-back You will advance to your current top performance level quite fast and it takes some persistence to get to the next level. On the other hand, the length of the sequence to remember (i.e. difficult level) for each round is deliberately changed quite easily so that there is minimal chance to learn strategies which are actually not increasing your fluid intelligence in the long run.