At first, when you start your game, you must take a quiz. This quiz determines the Pokemon you will turn into and who your Partner will be. You will be met by your partner on the beach, knocked out with no memory except for your name and the fact the you were once a human. Your Partner, who has always wanted to join the guild and make an exploration team, asks you to make one. You and your partner will eventually go on many missions, trying to find out who you are. In the future, they find out many shocking things, and who you really are.
The main game revolves around travelling through dungeons as you strive toward your goal of becoming the best rescue team ever. Dungeons are separated into floors and linked by ladders, but you can't go back, so they're one-way. To get through these dungeons you use the aid of your team partners, you have a partner from the beginning and other Pokemon will want to join your rescue team as your progress through the game. You also use items, though not all items are helpful. Your base is the Wigglytuff Guild which has shops, a place to save and plenty of other Pokemon to talk to. You can also interact with friends by helping each other or trading.
- A total of 491 Pokemon! - See Pokemon from Kanto, Johto, Hoenn and Sinnoh!
- Improved storyline - The new Pokemon Mystery Dungeon sports a much more in-depth storyline which has also been vastly expanded to increase enjoyment and overall playing time, along with replay value.
- Improved cutscenes - The cutscenes have been improved greatly in the second generation with bright, vibrant, colourful and evocative scenes which really take the game to a new level.
- Improved characters - Character personalities are more unique and developed this time round. From the scared out of his wits Chatot to the steely and boisterous Loudred it has a personality to relate to for any gamer.
- New starters Four new starters to choose from! Turtwig, Chimchar, Piplup and Munchlax.
- New dungeons - All new dungeons to explore and gaze in awe at!
- New items - Loads of new items with rarities such as the Golden Mask and Miracle Chest.
- New job type - Along with the usual missions such as rescuing, escorting or item finding there is a new type of job. It’s called arresting criminals! You’ll be hired by a Pokemon or Magnezone’s Police Squad to capture a dangerous Pokemon or take back a stolen item.
- Wigglytuff’s Guild - Wigglytuff’s Guild is the place you will eat, sleep and work at. It replaces the hut of last generation with a headquarters fit for a very eccentric Wigglytuff. It’s also removed the need for Pelliper’s Post Office, with jobs now obtainable through the job boards in the guild. It’s also replaced the Friend’s Area of Treasure Town with Chimecho’s Assembly.
- Treasure Town - Treasure Town has been given a makeover since last generation. It now incorporates six new characters and three new shops. It is now Duskull’s Bank rather than Persian’s, Electivire’s Link Shop rather than Gulpin’s and Marowak’s Dojo rather than Makuhita’s. The three new stores are Chansey’s Hut, Xatu’s Locksmith and Croagunk’s Trade Post.
- Standby Adventure - A feature that allows you to visit dungeons while waiting to be rescued (you can’t, however, gain levels).
- SOS Mail - When defeated in a dungeon, you have the option to send out an SOS message. This can come in the form of a password, across wireless connection or an email to your friend’s computer or mobile phone! They then send you an A-OK message in return to tell your game you’ve been saved and can begin playing again. The rescued player than has the option to send a Thank You mail if they so wish.
- Wi-Fi - Pokemon Mystery Dungeon: Explorers of Darkness makes use of the Wi-Fi capabilities presented by the Nintendo DS.
- Trading items and teams - Using wireless or Wi-Fi, people can trade teams/items with their friends. This gives you the opportunity for obtaining hard-to-find items and Pokemon that aren’t in your version or are a real pain to recruit.
This game is also known as Pokemon Fushigi no Dungeon: Toki no Tankentai (Japan) in Japan.