Why Brain Games? Brain games and brain teasers have captivated the attention of millions of people around the world from different ages and backgrounds throughout history. These kinds of games are not only fun and entertaining for the readers, but also help them to increase their intelligence, and develop their problem-solving skills, logic, attention, accuracy, memory, focus, analysis, computational speed, strategy, etc. Brain games and brain teasers sometimes can replace the traditional education system in which people can learn the same information but enjoyably in the form of a game. For example, mathematical calculations and multiplication tables are learned at schools. However, students don't like to memorize or to study them. Hence, to incite the students to learn and memorize the multiplication table, new games were created in a way to do the main job amusingly and enjoyably. Why this book, and why a new brain game? There are lots of new brain games that are created every year. Some of them are designed for a particular purpose, while others are just for fun. Nowadays, most of the brain games appear in the form of computer software or mobile application. However, there are lots of people who prefer to have the game in the form of a book. The book format does not allow competition between many players. The main goal of this book is to let the player compete with other players using a book and not an online application. Hence, the game should be designed to allow multi-players and to create a competitive environment with his friends and family.What is new in this book? In this book, "Connect-D2 in a Row" is a new brain game created by the author, which somehow looks similar to "Connect 4". However, instead of a rectangular shape, a diamond shape is used, and new rules are developed. Hence, the game becomes more complex and challenging. In addition, different grid sizes are presented to raise difficulty levels. This book includes 500 Puzzles. The first section is designed for only 2 players, while the second is suitable for 3 players. Finally, the last one is for 4 players. The book starts with the easiest levels and ends with the hardest and most challenging levels. The game is formed by a grid that contains at least one filled box which cannot be used by the players, while Connect 4 does not have any filled boxes. This new variation creates additional challenges for players. Therefore, new strategies and methods should be developed to win the game. People who love brain games and social games and who want to improve their intelligence, concentration, memory, reflection speed, etc., are invited to try this new game and provide their comments and suggestions to the author.LET'S TRY SOMETHING NEW AND CHALLENGING!!!