Sonic the Hedgehog 4 goes episodic this summer - GameSpot

Project Needlemouse revealed as side-scrolling sequel to speedster's original Genesis trilogy; Episode 1 confirmed for Wii, Xbox 360, PS3.
Sonic is back for his fourth installment in the classic 2D series, revamped from the ground up.

Sonic the Hedgehog 4: Episode 1 - Game - Nintendo World Report

Sonic the Hedgehog 4: Episode I (Game) - Giant Bomb

Sonic the Hedgehog 4: Episode I - Wikipedia

SONIC 4: EPISODE I - Full Game (100%, All Chaos Emeralds)

Editing Sonic the Hedgehog 2006 (lost build of Tokyo Toy Show tech

Sonic the Hedgehog 4: Episode 1 News - GameSpot

Is Sonic 4 a mainline game?

Sonic Mania review round-up: Sonic's big return to 2D leaves critics

Sonic 4: Episode 2 Archives - Sonic Retro

Needlemouse Revealed!!!

Sonic the Hedgehog 4: Episode II Review - GameSpot

Sonic the Hedgehog 4: Episode II Review - GameSpot