Pokémon Mystery Dungeon: Explorers of Time (ポケモン不思議のダンジョン 時の探検隊 Pokémon Fushigi no Danjon Toki no Tankentai?, lit. "Pokémon Mystery Dungeon: Time Exploration Team") and Pokémon Mystery Dungeon: Explorers of Darkness (ポケモン不思議のダンジョン 闇の探検隊 Pokémon Fushigi no Danjon Yami no Tankentai?, lit. "Pokémon Mystery Dungeon: Darkness Exploration Team") are a matched pair of Pokémon games for the Nintendo DS. The two games were released in Japan on September 13, 2007, and were released in North America on April 20, 2008. They were released in Europe on July 4, 2008.
A sequel to Pokémon Mystery Dungeon: Blue Rescue Team, new features include the addition of Generation IV Pokémon, improved Wi-Fi functionality, and more touch-screen options. 491 of the 493 Pokémon are featured, as Shaymin and Arceus were not officially released at the time of the game's launch.
Source: Wikipedia, "Pokémon Mystery Dungeon: Explorers of Time and Explorers of Darkness", available under the CC-BY-SA License.