Alex Kidd in Miracle World isn't the best game on this list if I'm being objective, but it holds a special place in my memories. It's the first game I 'owned' and played, for my first console (SMS II). Brutally difficult. Almost impossible really in that original form, but I didn't realise that at the time. But very addictive, filled with a wide range of varied locations and activities, tough platforming, and catchy music.