The Sonic Forces demo which released earlier on Nintendo Switch is now available for PlayStation 4 as well, in the Japanese region PlayStation Store. However, English is a selectable language for the PS4 demo.
As before, the demo allows players to play as each of the three playable characters for one minute each. Modern Sonic dashes through Green Hill, Classic Sonic takes on Dr. Eggman in a boss battle, and the Avatar character battles his way through baddies in the Space Port stage.
As an aside, there is a Sonic series speedrunner, DarkspineSonic, who has managed to finish Green Hill within the one minute time limit, which is pretty amazing:
Sonic Forces is set to release for Nintendo Switch, Xbox One, PlayStation 4 and PC on November 7, 2017.