They can opt to pacify or subdue monsters in order to spare them instead of killing them. The combat system involves the player navigating through mini-bullet hell attacks by the opponent. Some monsters might engage the player in a fight.

The player meets various monsters during the journey back to the surface. The player controls a child who has fallen into the Underground: a large, secluded region under the surface of the Earth, separated by a magic barrier. Undertale is a role-playing video game created by indie developer Toby Fox.