Undertale

Years after a devastating war between humans and monsters, a child has fallen through a hole and into the monsters' underground world. Under the care of a kindly monster woman named Toriel, they learn the basics of the underground world, including that they may be attacked by other monsters who are less friendly. After the child leaves Toriel's care, it's up to them how they proceed through the underground, including whether they kill the monsters in their way or try to find peaceful resolutions to conflict.

Alternatively, players may choose to perform friendly actions in battle or show mercy to the opponent in order to resolve conflict without bloodshed. It is possible to finish every encounter in the game without killing anyone, though some monsters are more difficult to do this with than others. The player may need to perform certain actions in the overworld before some monsters can be befriended.