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 place in a 2D-perspective of Green Hill Act 1 during the late-afternoon time. The player must control Classic Sonic to jump on swingsets to get through the Challenge Act within the set time. Collecting clocks will shorten your time limit, but Badniks such as Moto Bugs and Crabmeats will stop you from reaching the Goal Plate in time. If the player reaches the Goal Plate in a minute and forty seconds, he/she will receive an "S" Rank.
- A remixed version of Neo Green Hill Zone 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.