Tetris is widely regarded as the game which sold the Game Boy to the world and turned it into a commercial smash hit, but for me personally, it was Mario's first DMG-01 outing which made me desire the portable system more than water, food and oxygen.
The year was 1991. I'd just moved house and was about to start at a new school, and as always there was that thorny issue of making friends. I'd moved to a new part of the town of Hinckley, Leicestershire and as a consequence knew nobody; bonds had to be formed using the traditional weapons of the pre-teen era: football (soccer to our American readers) and video games. As I had, at that point, only a passing interest in the former, it would be the latter that really broke the ice with my newfound neighbours.