Sonic Generations is a platform game in which players control two variants of Sonic the Hedgehog: "Classic" or "Modern".[2] Classic Sonic's gameplay is restricted side-scrolling gameplay similar to the original Sonic the Hedgehog games released in the 1990s,[3] and requires him to use moves such as the Spin Dash and the Spin Attack.[4] Modern Sonic's gameplay follows the gameplay style of Sonic Unleashed (2008), and Sonic Colors (2010),[5] featuring an amalgamation of third-person and side-scrolling perspectives and techniques such as boosting and homing attacks. Both Sonics collect rings as a form of health,[6] and power-ups such as elemental shields, invincibility, speed shoes, skateboards, or Wisps. Players can also customize each Sonic's abilities, and purchase additional ones at a Skill Shop.[7][8]
The game's main hub is a realm called White Space, in which the player can explore, converse with other characters, and access the game's levels, each of which are derived from a previous entry in the series.[9][10] The levels are split into three separate eras: the Classic Era (focusing on levels from games for the Sega Genesis);[11] the Dreamcast Era (focusing on levels from games for the Dreamcast, PlayStation 2, GameCube, Xbox);[12] and the Modern Era (focusing on levels from games for the PlayStation 3, Wii, Nintendo DS, and Xbox 360).[13][7] Each level consists of two acts (one for each Sonic), and ten additional missions such as collecting a certain amount of rings or completing a level with the help of another character.[14]
Upon reaching the end of the level, players are given a grade based on their performance, with an "S" rank being the best and a "D" rank the worst.[7] After completing an era, players must defeat two bosses: a "rival" character and a main boss.[10] Defeating each boss gives the player a Chaos Emerald,[e] all seven of which must be collected to confront the final boss.[16] In the console version, once the game has been completed, both Sonics can transform into their super forms by collecting 50 rings in a normal level. As Super Sonic, the player is invincible and their speed is greatly increased. However the Sonics lose rings while in this form, and will revert to their standard form when all the rings are gone.[16]
Hidden around each act are five Red Star Rings.[7] Collecting these unlocks concept art, music, or, if all five are collected, a new ability. The concept art, as well as cutscenes and character profiles, can be viewed in a Collection Room, while music can be set to play in any level, mission, or boss. The game also features two forms of online leaderboards: "Ranking Attack", which challenges players to obtain the best time and score on each level, and "30 Second Trial", which challenges players to see how far they can get through a level in 30 seconds.[16] An emulation of the original 1991 Sonic the Hedgehog game, ported by Backbone Entertainment, can be unlocked in the PlayStation 3 and Xbox 360 versions of the game.[17]
