Green Hill Zone (Classic Sonic's world)

Green Hill Zone (グリーンヒル), also known as just Green Hill (グリーンヒル), is a location in the Sonic the Hedgehog series. It is another version of Green Hill Zone from an alternate dimension set in the recent past.

Description
Green Hill Zone is a picturesque paradise with green fields and beautiful blue lakes. It also features big waterfalls, palm trees, rotating flowers, flora in various colors and totem poles of unknown origin. Perhaps most distinctively, the soil is checkered brown. Obstacles include crumbling platforms and spikes in the original iteration.

Past
Green Hill Zone's early history was most likely largely the same as its mainstream counterpart's up until at least some time after the West Side Island incident.

Sonic Generations
In Sonic Generations, Sonic went on a run through Green Hill Zone until the Time Eater emerged in the sky above the region and sent Sonic to the White Space.

After the Time Eater had been taken care off, Sonic and Tails returned to Green Hill Zone through a Time Hole left behind by the Time Eater.

Sonic Mania
In Sonic Mania, Sonic the Hedgehog, Tails and Knuckles got transported to Green Hill Zone with the Hard Boiled Heavies after the aforementioned group of Egg-Robos unearthed the Phantom Ruby on Angel Island. This would be the first Zone the trio visited on their new adventure.

Upon their arrival, Sonic, Tails and Knuckles (who had ended up in another location) noticed that the Phantom Ruby had transformed the Hard-Boiled Heavies into more dangerous forms with free will. As the villainous group made their escape, Sonic and his friends would pursue them through Green Hill Zone in order to keep the Phantom Ruby from falling into the wrong hands. At the end of Green Hill Zone, the trio got attacked by Dr. Eggman and his Death Egg Robot, but were able to defeat them. Sonic and co. would afterward follow Eggman and spy on him while he took the Phantom Ruby from his Hard-Boiled Heavies, who had now gone rogue and wanted the gem for themselves. Once Eggman got the Ruby however, the gemstone's powered caused Sonic and co. to be sent to Chemical Plant Zone