Sonic the Hedgehog 2 (16-bit)/Development
From Sonic Retro
Sonic the Hedgehog 2 has gone through several changes over its development process. There are several rejected ideas, levels, and other things that were left on the cutting room floor. The following details several of these things.
Time Travel
The concept of Time Travel in Sonic 2 was referred to in early concept art, as well as several gaming magazines including a July 1992 EGM article. Only past and present timezones are referred to in the concept art, so it may not have had as many alternate time zones as Sonic the Hedgehog CD. It isn't known at what point the time travel concept was dropped, but the 1992 EGM article refers to the game as being 40% complete whilst mentioning time travel being associated with the game. The concept art refers to the scrapped level Rock Zone as being the past version of the scrapped Desert Zone.