The first chronological view of Earth in Sonic the Comic was when Sonic the Hedgehog and Amy Rose appeared there when investigating the planet's New Zones. Ancient Egypt was under contol of three alien invaders (Set, Hathor and Thoth) who were masquerading as Gods. The villains were attempting to force the native humans to build them pyramids, but were ousted when Sonic tackled Set and stole his Staff of Power. Sonic and Amy also visited a native American tribe but were accused of meddling in their affairs and were captured. Only when Chief Thundercloud accepted that their tribe had actually been helped by spirits did he let Sonic and Amy free. Amy had already visited the Wild West in 1860 with Tekno the Canary, exposing the evil Colonel Granite's plans for world domination. Unfortunately, on forcing Granite back to his own time and returning Mobius, they gave the humans the means to invade Mobius.
At the beginning of 1999, Granite led an invading army to Mobius and captured many of the Emerald Hill Zone's defenders. In return, Sonic forced his way to Earth and ordered a protestor to take him to the Prime Minister in Downing Street, London. After being informed that Granite had another base in Scotland, Sonic raced there and defeated the troops (with a little help from Nature). Little over a year later, Earth would find itself being drained of all life on the planet. Unknown to anybody on the planet, the evil Doctor Robotnik had used The Plax to build a machine that channelled all of Earth's energy to his new Zone on Mobius. Sonic and his gang visited Easter Island to shut down the machine permanently.
Based on her visit to Earth, Tekno created a "game within a game" based on three Earth children. One of them would play a game starring Sonic pitting him against a Badnik. The game would then cut to humans who would have to fight a Badnik of their own.
Many of the Sega Superstars strips were set on Earth, at least partially. Only Sparkster (Elhorn), Wonder Boy (Monster World), Ristar and perhaps Golden Axe (Yuria) had their own locations, even if many of the other strips took them away from Earth at one point.