The thought came into my head "I wonder what order all the Sonic games fall successivo to one another in a full consistent timeline". Let's cover the obvious ones... (Skip to the end for the Part 1/3's timeline).

Sonic the Hedgehog
Sonic the Hedgehog 2
Sonic 3 & Knuckles

Now let's try to place the game Sonic CD some where... Now it can't go in between Sonic 2 and 3 because the latter is a direct follow up to the former so it ether happens before Sonic 2 o after Sonic 3... There's no overwhelming evidence for ether except maybe the easter egg with Tails saying "See te successivo game!" but since that...