Undertale is a Role-Playing Game by Toby Fox, funded on Kickstarter and released on September 15th, 2015. A demo is available at http://undertale.com/, and a trailer is available here. Is currently available to purchase in several platforms (including Steam), and a port to PlayStation systems (namely PlayStation 4 and Vita), along with an official translation to Japanese, was released in August 2017. A port for the Nintendo Switch was released in September 2018.

Years ago, Humans and Monsters ruled the earth together. One day, war broke out between the two races and humanity emerged victorious, sealing the monsters underground with a magic spell. In the present day, a small child playing in a cave trips and falls down an enormous hole. They wake up on a bed of flowers in a mysterious place...

Undertale draws heavily from EarthBound and Mother 3, but the core gameplay is very different from typical RPGs. Instead of selecting commands and having the computer calculate hits, each enemy attack brings up a smaller arena where the heart-shaped avatar of your soul must dodge projectiles like in Bullet Hell. In battle, the player can choose to FIGHT an enemy or SPARE them after ACTing in a way that let you do that.

The game has received critical acclaim and a dedicated fanbase has revolved around it, becoming popular among letsplayers. Currently, it is the most well-received video game made on Game Maker.

You can read more about Undertale through the Undertale Wiki, but tread cautiously, as it is chock-full of spoilers.

An spinoff game titled Deltarune was released in October 31, 2018

Tropes used in Undertale include:

First, a very special trope: