The default listed name for each game is the one by which it is most commonly known to Genesis and MegaDrive fans on the Internet.  This is usually the the U.S. market title in most case unless the game was not released Stateside.  In that event, the default listed name is for the market (Europe, Japan, etc) in which the game was first released.  Also, if a title in another market is better known, then that one may be used instead of the official one.  You will find all known variant names listed in the Alternate Titles column. 
 

Here is a listing of all the various unlicensed titles that were rumored, announced, or released for the Sega Genesis/MegaDrive/Nomad systems in all markets.  You can read the available SegaBase™ full-length reviews by clicking on the appropriate title.  If there is no review yet on file, then there will be no review linked to that title.  The default listed name for each game is for the U.S. market unless it was not released Stateside.  In that event, the default listed name is for the market (Europe, Japan, etc) in which the game was first released.  You will find variant titles listed in the Alternate Titles column. 

Please note that early Accolade titles are not included in this list since the company eventually secured a Sega license.  You will find them listed under the commercial releases.

This list includes bootlegs of commercial titles that were not originally licensed for the system.  This list also includes all known adult titles for the console.  Adult titles were never approved by Sega for obvious reasons.