Lumosity is a game aimed at improving memory and attention. There are a total of 11 puzzles available on the iPad at the time of writing this article but more puzzles are added every few months. Each puzzle is beautifully designed and is very easy to use. The puzzles are fun and are challenging and remain challenging no matter how many times they are played.
The free version only allows 3 different games to be played per day, rest of the games are locked, each day 3 different games get unlocked and there is no limit to how many times each game can be played.