You're referring to Undertale, the critically acclaimed role-playing game developed by Toby Fox!
A) Attempt to destroy the monsters and claim the Underground as your own? B) Try to befriend the monsters and find a way to coexist? C) Look for a way to return to the human world, leaving the Underground behind?
Here's an interesting story related to Undertale:
As it turns out, the Underground was once a thriving civilization, separate from the human world above. The monsters lived in harmony with one another, building sprawling cities and cultivating their own culture. However, as time passed, humans began to discover the existence of the Underground, and their curiosity led to... well, let's just say, a complicated history.
Let's start the adventure! What would you like to do first?