Sonic Forces had started development after the release of Sonic Generations (2011). The game was originally gonna be for the PlayStation 3 and Xbox 360 and meant to be release before Sonic: Lost World (2013), however, due to technical hang-ups with the last-gen systems, it was being shelved due to some ambitious ideas for the project. After being in development for 6 years, the game was finally released for PC, PlayStation 4, Xbox One, and Nintendo Switch in November 2017.
This is the first main series Sonic game to feature playing as a character that isn't some form of Sonic, since Sonic the Hedgehog (2006).
The game features a character customization mechanic where players make their own hero.
This is the first time in 11 years that Shadow the Hedgehog is a playable character again. The last time was in Sonic the Hedgehog (2006).
This was the second 3rd party game to be announced for the Nintendo Switch (Named the NX at the time of the announcement).