First Metal Gear game to provide an in-game clue on the game box

The Metal Gear Series encouraged players to think outside the box from the very beginning, but with Metal Gear 2: Solid Snake for the MSX2, this reached a new level. PlayStation fans who remember being astonished that the rear of the box contained a radio frequency that proved essential to play the game may be equally surprised to find that the idea debuted as early as 1990. The MSX2 game stayed exclusive to Japan until its global re-release in 2005.