Here's what worked for me;
I loaded up each one of the Sega Mega Drive titles. I didn't actually play them, simply getting to the start screen was enough. I found doing them in alphabetical order was the easiest way to keep track. Simply load each title until you get to the start screen for that game, then exit the title using the back button... then sellect the next title... keep going until the achievement unlocks.
I had already played some of the titles when I went for this achievement, so to start with I only loaded/played the one's I hadn't already previously played. The achievement didn't actually unlock until I had loaded/played every title in the same session. Even by playing/loading each title, this achievement shouldn't take any longer than 10-15 mins.
Hope this helps.