You might not see the supporting merchandise so much nowadays but Pokemon is still the most successful games franchise in history. Diamond and Pearl sold 5 million copies in Japan in under three months and 1 million in America in just one month, breaking all records for the year and the series. At first sight though this looks disappointingly similar to the existing games, with only a subtle 3D effect for the game world and largely static 2D battles. However the gameplay has undergone a complete overhaul, adding numerous new features and reintroducing others from Gold/Silver/Crystal, that had previously been removed.
The basics are still the same though, as you venture out into the world (called Sinnoh this time) in an attempt to catalogue each and every pokemon and battle the evil Team Galactic. Catching and training a pokemon for combat also works the same as before, although beauty and talent contests have been greatly expanded for those that prefer as little violence as possible. The game includes a day and night cycle, which severely impacts the appearance of pokemon, and you are given a new gadget called a poketch which starts as a simple watch but can be upgraded to everything from a scanner to a map. Secret bases are back and considerably more sophisticated than before but the most important new feature by far is the online mode. You can now trade, chat and battle with fans from around the world proving that progress is not always just a case of better graphics. Harrison Dent