Underground Adventure is an NES homebrew game made for the 2019 NESmaker Byte-Off Competition. It has a simple setting of two guys finding a cave that leads to an underground maze full of gems and monsters. They must then collect as many gems as they can under a time limit, avoid (or kill with a special item) any monsters along the way, and go back the way they came.
MarioAtWork decides to just clip through the bottom of the screen and glitch their way back to the exit, beating the game in record time.
You can get the game here.