Quacky's Quest is a maze game in which a duck collects diamonds and avoids spiders. Grandmother Sherry is able to navigate the maze by the distinctive sounds made by diamonds, nearby spiders, and solid walls. Rocks fill the space behind the player to avoid the confusion caused by walking in a space whose diamond has already been collected.
Viale designed the game with sprites and tiles (above), then turned them off for the final version, which Sherry had no trouble playing. He then entered it in his elementary school's science fair, where of course it won first place.
There are relatively few games that can be played with audio only – the Japan-only Game Boy game Soundvoyager is perhaps the most famous one. However, it's unlikely Dylan Viale knew about any of those, so he essentially invented the genre independently. That's worth a science fair medal.