Penguin Adventure (夢大陸アドベンチャー Yume Tairiku adobenchā?, lit. "Dream Continent Adventure") is an action-adventure platform game released by Konami in 1986. It is a sequel to Antarctic Adventure and has the distinction of being the first game that Hideo Kojima ever worked on.
During the briefing for the second act of Metal Gear Solid 4: Guns of the Patriots, Sunny can be seen playing Penguin Adventure on her PlayStation Portable. If the player gets close enough with the Metal Gear Mk. II, music from the game can be heard. In real life, however, Penguin Adventure was never released onto the PSP during that system's lifetime.
Aside from this, the game's ending also varied depending on the player's actions. If the player found less than four hidden treasures during gameplay, Princess Penguinette will end up dying in her coma. However, if the player managed to find at least four hidden treasures, Penguinette will recover upon eating a golden fruit. This situation would later be repeated with Metal Gear Solid with a similar situation involving the character Meryl Silverburgh (she'll die if Snake gives in to the torture, while she'll live if Snake endures through it), as well as Metal Gear Solid 2 to a lesser extent.