TARS X Undertale is a story where some of the TARS cast go to the world of undertale. *Contains Undertale Spoilers!*
White Kirby, Blue Kirby, Dyna Blade, Kirby, King K. Rool, Bayonetta and the Shadow Star are racing up Mt. Ebott to find the sexy treasure at the top. However, Kirby finds a hole. Kirby says that it might be a "shortcut" and everyone jumps in. They land in the ruins and meet Flowey. The encounter with Flowey goes basically the same as in the game. Flowey tells everyone to have some of his Friendliness Pellets. Kirby says he is allergic, and Dyna Blade says Friendliness Pellets are for gay people. So they dodge Flowey's Gay Pellets. At the point where Flowey accidentaly says they are bullets, before his text changes Bullets to Friendliness Pellets, the cops arrive, and since Flowey said Bullets, he is arrested for possessing weaponary. Dyna Blade goes on to kill every enemy in the ruins while Toriel comes to greet the other characters. Kirby calls her a fat cow and kicks her into the fireplace, and then the other characters leave the ruins.
Meanwhile, in Snowdin, Dyna Blade is going on a murder spree, while the other characters have to go through puzzles. The first puzzle involves dodging all the red tiles, however, Kirby hacks into the system and makes all the tiles pink. The second puzzle involves dodging rolling bowling balls. Kirby swallows the bowling balls as the other characters follow from behind. 1 billion puzzles later, they finally arrive at Snowdin. The characters go to the local shop in Snowdin to sell items they don't need. However, in Undertale, you cannot sell your items to any shop with the exception of the Tem Shop. Due to this, Kirby threatens her with a knife and tries to attack. However you can't fight the shopkeepers, so the Snowdin Shopkeeper blasts everybody away with a Gaster Blaster. After this, the characters run into Papyrus and meet back up with Dyna Blade. Papyrus challenges them to a fight when Dyna Blade stabs him. Papyrus, injured, runs away.
Meanwhile, everybody enters Waterfall. Dyna Blade goes to kill everybody when the others run into Undyne. The monsterz need 7 moar souls to break the barrier, so Undyne starts throwing spears at the characters. However, to her surprise, the characters fight back and pull out their bazookas and shoot at Undyne. After humping through Waterfall and choking a dog for stealing a ball, they run into Napstablook.