In normal levels, players must reach the treasure chest at the end of the stage, while using features such as springboards and boost pads, and avoiding obstacles such as robots, spikes, and bottomless pits. In boss fights, players must defeat a large robot by jumping on its vulnerable spot to deplete its health meter. When completing a level, players are given a grade based on their performance; an "S" rank is the best, while a "C" is the worst. Both of the DS's screens are used to display the play area, with the player's character moving between them as necessary. The game's setting is an archipelago of an alternate dimension from that of Sonic's. The main island of the archipelago is Southern Island, which houses the village that serves as a headquarters for Sonic and the others, known as Windmill Village. The player begins each adventure from Windmill Village on Southern Island. Players can plot their routes to each level using the DS's stylus and travel to one of the islands using one of the four ships, each of which uses a different touchscreen-controlled minigame. Ships can be built using materials that are earned by completing levels. On different areas of Southern Island, players can talk to members of Marine's Coconut Crew, who will offer Sonic tips and additional missions as the story progresses. The game features 100 of these missions, with objectives such as completing a stage within a time limit or defeating a boss with only one ring. Certain missions must be finished to progress through the story, while others offer bonus rewards upon completion, such as musical tracks the player can listen to or visual upgrades to Southern Island. At Marine's house, players can talk to Marine to initiate missions, have Tails build new ships and equipment using materials gathered from stages to advance the story, or engage in multiplayer battles using DS Download Play or Nintendo Wi-Fi Connection. By deviating from the recommended objective on the Sea Chart, players can find hidden islands to explore and earn additional materials, as well as run into a robot pirate named Johnny. Finding Johnny will trigger a race between him and Sonic, with the player receiving one of the seven Chaos Emeralds if they are victorious. Blaze can earn Sol Emeralds by completing a series of special missions. If the player has reached the normal ending and collected all