The Doomsday Project

"The Doomsday Project" is the 26th (and final) episode of Sonic the Hedgehog. It aired on December 10, 1994

Plot
when a pod lands in knothole, Sonic and Sally realize that Robotnik's Doomsday Project has begun a week early! With all of Mobius in danger, the Freedom Fighters prepare for what may be their final battle. The Freedom Fighter groups decide to infiltrate into the Doomsday Machine, and, with both of the Deep Power Stones, Sonic and Sally destroy the machine. Meanwhile, as Robotnink and Snivly are arguing over what to do, the enraged Snivly escapes with his life, as Robotnink's last words: "I HATE THAT HEDGEHOG!", followed by repeating "HATE!".

Back at Knothole, Sonic and Sally anounce the defeat of Robotnink, followed by a passionate kiss between Sonic and Sally.

The episode ends as Snivly rises from the rubble, seemingly breaking the fourth wall as he says "Now, it's MY turn!"

Trivia

 * At the end of the episode, a pair of red eyes is seen by the viewer. This was confirmed by SEGA to be Ix Naugus, who was supposed to be the lead antagonist in the next season. Ix Nagus was later ported to the comics, and he is now a main antagonist after the "Genesis" storyline.
 * As Sonic and Sally kiss, Antione seems to not care, this may be a hint that Antione WAS the love intrest of Sally for season 3.