Bad Time Simulator

About the Bad Time Simulator Game

Bad Time Simulator is an unofficial Undertale fan game that allows players to experience the iconic boss fight against Sans, the final and arguably most difficult enemy in the game’s Genocide route. The simulator is designed to be played directly in your browser, with no downloads needed, making it perfect for on-the-go gameplay or casual retries of one of gaming’s most notorious battles.

The game replicates the original encounter with impressive accuracy. From Sans’ bone attacks and gaster blasters to the eerie ambiance and minimal healing options, it mirrors Undertale’s mechanics while introducing new features like Revenge Mode an even more punishing version of the original fight.

Game Features

Bad Time Simulator isn’t just a copy-paste of the Undertale fight—it comes with its own set of improvements and challenges designed specifically for fans of difficult games and hardcore Sans stans.

Authentic Boss Mechanics – Dodge bone attacks, survive gaster blasters, and navigate complex patterns like in the original Undertale fight.

Revenge Mode – A hardcore mode where you fight with limited or no healing, adding a layer of challenge even veteran players will struggle with.

Minimalist, Fast-Paced Design – No filler content. Just pure boss battles and reflex-testing gameplay.

Browser-Based Access – Play instantly on desktop or mobile browsers with no installation.

Perfect for Undertale Fans – Designed to replicate the visual, audio, and battle flow of Undertale, with many reviewers praising its faithfulness.

Explain the Game Objectives

The main goal in Bad Time Simulator is simple but brutal: survive Sans’ relentless attacks and defeat him. You control a small heart (your soul) and must dodge increasingly complex attack patterns while taking advantage of brief moments to retaliate.

There’s no exploration or story progression here—this is a battle-focused experience designed to test your ability to learn patterns, stay focused, and persevere through repeated failures. Beating Sans is an achievement in itself, especially in Revenge Mode.

Easy Game Controls

Bad Time Simulator uses simple controls that resemble the original Undertale gameplay:

• Arrow keys / WASD – Move your soul (heart) during attack sequences.
• Spacebar / Enter – Confirm menu options and actions.
• Mouse (optional) – Navigate menus or select options quickly.

The game is designed for fast-paced, responsive input, though some players report that mastering the controls, especially on mobile, can take a bit of practice.

What Reviewers Are Saying

Fans of Undertale have embraced Bad Time Simulator as a faithful and fun way to relive one of the game’s most iconic moments:

“As a huge Undertale fan, I really enjoy this game. Everything is really accurate to Undertale which I really appreciate… Overall, this is a great game if you want to fight Sans on the go.”

Other players love the challenge it offers, especially in the enhanced difficulty settings. However, feedback suggests the controls can take getting used to, and the lack of healing in Revenge Mode makes it extremely difficult even for experienced players.

Some suggestions include adding more healing items like Snowman's Piece, Butterscotch Pie, or even custom options like cupcakes to make the experience more balanced for new players.

If you’ve ever wanted to fight Sans without replaying the full Genocide route, the Bad Time Simulator game is your chance. With its faithful recreation of the original fight, challenging modes like Revenge, and minimalistic focus on skill-based gameplay, it’s a perfect pick for both seasoned Undertale players and anyone looking to test their reflexes.

Click Play Now and find out just how many tries it takes you to win!