This page details development materials of Sonic the Hedgehog 4: Episode I.
Development Screencaps#
One of the most interesting of all. This one appears to be a placeholder for the leaderboard. Curiously, the username is "tedy", as a placeholder.
Internal Project name#
The internal project name is called SonicPortal, or Sonic Portal, according to source files.
The Sonic 4: Episode I project name is simply Sonic4, while Sonic the Sketchhog, aka Tegaki Sonic, is simply SonicFlash, as it suggests it was a completely different game!
There's also a dev comment explaining about its build date (November 16, 2010):
// SonicFlash
//
// Created by takahashi on 10/11/16.
//
This is likely a updated variant, as the actual game was available for a month of July 2010.