Mario & Sonic brings together the two titular characters and fourteen more from both franchises to participate in environments based on the official venues of the 2008 Summer Olympics in Beijing. These environments are stylized to fit the futuristic and cartoon-like art styles of the Sonic the Hedgehog and Mario franchises respectively. Each playable character has his or her own statistics which can serve as an advantage or disadvantage depending on the event. The characters are divided into four categories:
The Wii version has additional in-game characters taken from the console's Mii Channel, which allows the user to create a Mii, a customized avatar, that can be imported into games that support the feature. Both games have non-playable characters who serve as referees for particular events.
Mario & Sonic at the Olympic Games is a collection of twenty-four events based on the Olympic Games. On the Wii, the events consist of using the motion sensor capabilities of and to control the actions of the on-screen character. The player moves in a manner similar to the method the separate games are played in real life; for example, swinging to replicate the hammer throw or pulling back on it and tilting like a bow and arrow. While is required for archery, it is optional for most of the events. There are also events that are more physically demanding, such as the five running events which require rapid drumming of the controller. Some aspects of the gameplay are computer controlled. For example, in table tennis the player movement is controlled by the Wii, while the swinging of the racket is controlled by the player. The DS game is the same in design, but its events are less physically demanding than those on the Wii. For example, instead of drumming the controller, players have to quickly stroke the touchscreen.
Both versions of Mario & Sonic at the Olympic Games have three similar modes of gameplay:
- Circuit mode
- Single Match
- Mission mode
Circuit mode is where players compete for the highest overall score in a pre-determined series of events or design their own circuit. In the Single Match, players can choose to compete in each event individually. Mission mode is a single-player option where each of the competitors has six character-specific missions to complete, although the characters' statistics are not as balanced as in the main game, making missions more difficult. The Wii version's Circuit and Single Match can have an additional one to three players competing simultaneously while its DS counterpart has a extra option dedicated to multiplayer called Versus Play. Versus supports up to four people using the wireless capabilities of the Nintendo DS to play events. DS Download Play is possible for those without a individual copy of the game, however the number of sports available is limited.
Both versions feature a gallery mode where brief facts about the Olympics can be found. There are five categories of Olympics-related trivia organized by history and athletes, with corresponding minigames that will unlock the answer to trivia questions once completed. Classic music from both series is available in the gallery once all levels in a category are cleared. The two versions also have leaderboards that uses the Nintendo Wi-Fi Connection to display the best times and scores in each event.
Mario & Sonic at the Olympic Games features authentic Olympic events for the Single Match and Circuit modes. The types of events are classified as athletics, gymnastics, shooting, rowing, archery, aquatics, fencing, and table tennis. Similar events have varying gameplay aspects; for example, getting a starting boost in the 100m dash is more important than in the longer relay races, since the initial short burst of greater speed would play less of a role in winning the longer distance runs. In relay events, such as the 4×100 metres relay and 4×100 metres aquatics relay, players can assemble teams comprising any four characters.
Besides these regular events, there are alternate versions of Olympic events called "Dream Events". Unlike the regular events, the gameplay in Dream Events is exaggerated. Taking place in locations and using objects from older games of the Mario and Sonic series, Dream Events allow players to use the special abilities of characters and display dramatic moments in slow motion.
Although the Wii and DS versions of the game feature mostly the same events, each version has events that are not found in the other. The relay races are exclusive to the Wii version. In contrast, the DS version has five Dream Events – canoeing, boxing, basketball, long jump, and skeet shooting – not featured on the Wii version.
|100m and 400m||Track & Field||Yes||Yes|
|10m Platform Diving||Aquatics||No||Yes|
|110m Hurdles||Track & Field||Yes||No|
|400m Hurdles||Track & Field||Yes||Yes|
|4×100m Relay||Track & Field||Yes||No|
|Dream Basketball||Dream Events||No||Yes|
|Dream Boxing||Dream Events||No||Yes|
|Dream Canoeing||Dream Events||No||Yes|
|Dream Fencing||Dream Events||Yes||Yes|
|Dream Long Jump||Dream Events||No||Yes|
|Dream Platform||Dream Events||Yes||No|
|Dream Race||Dream Events||Yes||Yes|
|Dream Skeet Shooting||Dream Events||No||Yes|
|Dream Table Tennis||Dream Events||Yes||Yes|
|Hammer Throw||Track & Field||Yes||Yes|
|High Jump||Track & Field||Yes||No|
|Javelin Throw||Track & Field||Yes||Yes|
|Long Jump||Track & Field||Yes||Yes|
|Pole Vault||Track & Field||Yes||No|
|Triple Jump||Track & Field||Yes||Yes|