The Metroid Prime Trilogy version of Metroid Prime 2 utilises the same credits-based system for unlocking bonus game material as Metroid Prime 3 (so everything here on this page only applies to the Wii version of Metroid Prime 2). All of the bonus art galleries taken from the original game are available to purchase.
Two types of credits exist for MP2: purple and silver. Purple credits are all picked up from defeated bosses, while silver credits are gained as you collect Dark Temple keys. See below for a complete list of how to go about collecting all the credits.
See the secrets and tips page for the list of all unlockable items, how to make them available for purchase and their credit cost.
A total of 15 purple credits can be collected. Each of the following bosses will grant you a single purple credit upon their defeat. Note that you can only collect these credits once per save file on any difficulty setting.
Silver credits are awarded as each Dark Temple key is collected. A total of 18 can be gained in this game, tallying up to a grand total of 34 when combined with Metroid Prime's silver credits.