Earlier Sega Mega Drive games shipped on smaller sized ROM cartridges, were selling at a vastly reduced price several years down the line and were often showing their age. Rather than waste money on producing cartridges for out of date classics, Sega thought it was a better option to compile several of these games onto one cartridge, as the decreasing price of the technology allowed Sega to make a healthy profit in doing so. This does not apply so much to third party games, such as Arcade Classics or Midway Presents Arcade's Greatest Hits - they had different agendas but still class as compilations.
The majority of Mega Drive game compilations were bundled with consoles, meaning if you bought a Mega Drive in 1995, you'd be given several games straight away to get you started. As many of these cartridges were not sold separately, they are often increasingly more rare than the stand-alone releases of the games they contain. This is made worse by the fact that some compilations turned up well into the Mega Drive's twilight years - focus was instead on the fifth generation of video game consoles and so many compilations went simply unnoticed.
Sega did not officially recognise "Compilation" in their late-1980s genre classification system, most likely because no Mega Drive compilations were released in Japan. This genre has been created by Sega Retro as it would otherwise be impossible to classify these releases (for example, Mega Games 10 has action, puzzle, racing sports games included).
The following 63 pages are in this category, out of 63 total.