What is the difference between Japanese and Western Pokémon Diamond and Pearl?

Diamond and Pearl launched in Japan on September 28, 2006, and in North America on April 22, 2007, and the seven months between those dates are written into the code. Japanese launch copies contain the Surf glitch, the programming mistake that let players surf through a door in the Pokémon League and walk the void to Darkrai and Shaymin. Nintendo removed it from later Japanese printings and from every Western copy, so the most famous Generation IV glitch simply does not exist in an English cartridge.

The same is true, in miniature, of the era's other acknowledged fault, a broken escalator Nintendo owned up to alongside the door. Japan's first printing of a Pokémon game was, in effect, a draft the rest of the world never played. What survived everywhere was tweaking, the subtler bicycle glitch that misloads map graphics; Western void explorers had to make do with it.

Beyond the patches, the differences are the ordinary kind: text and names localised out of Japanese, Pocket Monsters branding swapped for Pokémon, and the Mystery Gift and event calendars run on each region's own schedule. Japan's players were deep into the games' second year, with Platinum announced, before some regions had finished their first.

For collectors the split is the interesting part. A Japanese launch Diamond is not just the same game in another language; it is the only retail build of Diamond in which the void can be entered through the League door, a small piece of software history that the rest of the world's copies edited out.