Here is a list of all of the main line Sonic the Hedgehog games in order of release, including where and how to play them.
The Complete List of Sonic Games in Chronological & Release Order - Cheat Code Central
List of Sonic the Hedgehog characters - Wikipedia
Sonic Origins remasters four classics, out in June
A timeline of the last six years- and six before that- of the Sonic series. Whew- here's hoping we get a lot of good stuff in 2021. : r/SonicTheHedgehog
Every Sonic The Hedgehog game ever and in what order to play them - Meristation
All the Sonic Games - IMDb
𝖬𝗒 𝖱𝖺𝗇𝗄𝗂𝗇𝗀 𝖮𝖿 𝖤𝗏𝖾𝗋𝗒 𝖬𝖺𝗂𝗇𝗅𝗂𝗇𝖾 𝖲𝗈𝗇𝗂𝖼 𝖳𝗁𝖾 𝖧𝖾𝖽𝗀𝖾𝗁𝗈𝗀 𝖦𝖺𝗆𝖾
Tier list of every mainline sonic game. Is my list valid? : r/SonicTheHedgehog
Create a Mainline Sonic Games Tier List - TierMaker
All Mainline Sonic Games Tier List (Community Rankings) - TierMaker
Sonic The Hedgehog Timeline by The4thSnake on DeviantArt
The Complete List of Sonic Games in Chronological & Release Order - Cheat Code Central
The 10 Best Sonic Games
Sonic Frontiers - Wikipedia