Erika and Satoru's Dream Adventure

Two-player adventure games were seen as very rare at the time of the game's release; even in Japan. However, only one person could partake in the animal quiz portion. Failing the quiz will force the player(s) to start from the beginning. It is one of the few games for the Family Computer to use the Namco 163 wavetable sound chip, and is also one of the games that enables all eight sound channels provided by the chip, the other being King of Kings. The end of the game contains an easter egg in the form of a developer's lengthy profane complaint about his coworkers' behaviour. Source: Wikipedia, "[en.wikipedia.org/wiki/Erika_to_Satoru_no_Yume_B%C5%8Dken Erika to Satoru no Yume Bōken]", available under the CC-BY-SA License.