UT10 Battle - Undertale 10th Anniversary

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UT10 Battle - Undertale 10th Anniversary | Official Tribute Game

Released:September 24, 2025

Alternate universe Undertale

🎮 Controls: Arrow keys to move, Z to confirm, X to cancel

UT10 Battle Undertale 10th Anniversary Game Screenshot

Celebrate Undertale's 10th anniversary with UT10 Battle! This official browser-based mini-game from Toby Fox and Fangamer features two unique boss battles: a comedic Pacifist Sans Battle and the challenging Mr. Sunshine & Aberrant Battle. Experience Undertale's iconic combat system with new characters, music, and downloadable assets in this heartfelt tribute to the indie masterpiece.

Two Unique Battle Experiences

Choose between two distinct boss battles, each offering multiple endings based on your combat or pacifist approach. Perfect for both Undertale veterans and newcomers.

Pacifist Sans Battle

A hilarious twist on Undertale's infamous Sans fight, reimagined as a laid-back 'peaceful' opponent with Toby Fox's new 'Dr. Jogboy' design from the anniversary livestream.

•Bone attacks with quirky bulldozer mechanics to push your soul off-screen
•No Gaster Blasters or KARMA damage - focus on ACT options for funny dialogue
•MERCY for heartwarming resolution, FIGHT triggers quick 'bad time' ending
•Low-difficulty nostalgic nod to Undertale's Pacifist Route
•Multiple humorous endings to discover

Perfect for laughs and warming up before the main challenge!

Mr. Sunshine & Aberrant Battle

Straight from the livestream's Dog Hole area and inspired by Undertale Wildfire, this medium-difficulty fight features two original enemies with distinct personalities.

•Mr. Sunshine: A self-proclaimed sun-like entity (cheeky jab at overly optimistic fans)
•Aberrant: An arrogant 'anomaly' mocking lore theorists
•Dynamic bullet patterns including beams and chaotic shapes
•FIGHT to deal damage (killing both yields ~550 EXP and LV 8)
•ACT options like 'Compliment Sunshine' or 'Question Aberrant' for pacifist ending

Killing one enemy alters the other's attacks for deeper strategy. Offers at least three endings—pacifist, neutral, or kill—with fan-service Easter eggs and punishing messages like 'Haven't you learned anything over the past 10 years?'

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UT10 Battle - Undertale 10th Anniversary

UT10 Battle - Undertale 10th Anniversary | Official Tribute Game

Game Overview

Two Unique Battle Experiences

Ready to Experience the Ultimate Undertale Tribute?