Swingset Circus is the fourth Challenge Act of Green Hill Act 1 in the console/PC version of Sonic Generations. It is unlocked after clearing every Stage in the classic era and is playable only as Classic Sonic.
The player is placed in a highly modified version of Green Hill Act 1 during the late afternoon. The player must control Classic Sonic to jump on swingsets to get through the Challenge Act within the set time. Collecting clocks will shorten the player's elapsed time, but Badniks such as Moto Bugs and Crabmeats will stop them from reaching the Goal Plate in time. If the player reaches the Goal Plate in a minute and forty seconds, they will receive an "S" Rank.
The player begins on an elevated platform and must navigate across several sets of swinging platforms to get through the Act. Badniks are placed throughout the stage in order to hinder the player, and falling down will cause the player to lose valuable time. Patience and good timing are required to progress without falling down and having to backtrack.
- A remixed version of Neo Green Hill Zone's music from Sonic Advance is used as the main music in this Challenge Act.
- Along with Knuckles: Horde of Enemies, this Challenge Act takes place in a different time period than the usual Green Hill Act 1, as this Challenge Act takes place in the late afternoon.