Bad Time Simulator

4.5(1408)

Bad Time Simulator | Sans Fight & Undertale Boss Battles

Released:April 22, 2025

Alternate universe Undertale

🎮 Basic Controls: Arrow Keys/WASD to move your SOUL

⚔️ Battle: Z/Enter to confirm, X to go back

💡 Pro Tip: Click on the Bad Time Simulator game screen to activate keyboard controls

Play Bad Time Simulator and discover multiple Sans fight variants, Bad Time Trio battles, and all major boss fights from Undertale and Deltarune—including Jevil, Undyne, Papyrus, Mettaton EX, Berdly, and more. Experience these legendary bullet-hell challenges instantly online.

What is Bad Time Simulator?

Bad Time Simulator stands as gaming's most notorious challenge, recreating the final confrontation from Undertale's Genocide Route.

The Original Challenge

Originally developed by Jcw87, this browser-based simulator has evolved into a cultural phenomenon with hundreds of thousands of players worldwide and countless fan variations.

Core Gameplay

In this intense battle within the Bad Time Simulator, you control a small red heart (your SOUL) against Sans – a skeleton with incredible powers and his signature permanent grin. The game features 24 distinct attack patterns (13 in the first phase and 11 more challenging ones in the second phase), requiring precise dodging and pattern recognition. The iconic "MEGALOVANIA" soundtrack sets the perfect tone for this legendary showdown.

What makes it special

•Authentic recreation of Sans' fourth-wall-breaking dialogue and personality
•Two-phase battle system with escalating difficulty and unique mechanics
•Blue soul gravity mechanics that change movement physics mid-battle
•Karma damage system that punishes players based on their Undertale choices
•Frame-perfect timing requirements that test true gaming precision

How to Play Bad Time Simulator

Master the controls and game modes to survive the legendary Bad Time Simulator challenge.

Game Modes Available

•Normal Mode: The classic Sans battle experience in Bad Time Simulator. Dodge attacks and try to defeat Sans. You'll return to the menu automatically if you lose.
•Practice Mode: Hone your Bad Time Simulator dodging skills without pressure. Note: attacks loop indefinitely—refresh the page to exit.
•Endless Mode: Select Phase 1 or Phase 2 for an escalating challenge that tests your endurance against the increasingly difficult patterns of the simulator.
•Single Attack: Master specific patterns by choosing from 24 different Sans attacks. Great for targeting your weaknesses or starting with simpler patterns in Bad Time Simulator.
•Custom Attack: Load File: Import attack patterns created by the community; Documentation: Access creation instructions (unlocks after loading a file); Run Attack: Test custom patterns (available after loading a file)

Master Bad Time Simulator Strategies

•Use Single Attack mode to practice specific patterns you struggle with
•Stay centered during bone attacks—most patterns are designed around middle positioning
•In blue soul phases, jump timing is crucial—tap up arrow briefly, don't hold
•Focus on Gaster Blaster warning signs—they telegraph direction before firing
•Try unlimited HP versions first to learn Bad Time Simulator attack patterns without pressure

Bad Time Simulator Mastery: See All Attack Patterns in Action (Full Playthrough)

FAQ

Common questions about Bad Time Simulator

What does bad-time-simulator.com offer?

bad-time-simulator.com is your ultimate hub for Bad Time Simulator battles and Undertale/Deltarune boss fights. We specialize in the original Bad Time Simulator and its variants, plus boss fights from across the Undertale universe—all playable instantly with no downloads required.

What Bad Time Simulator versions are available?

We offer the classic original plus exciting variants: Bad Time Trio (Sans, Papyrus & Gaster), Bad Time Duo (skeleton brothers), crossover themes, unlimited HP practice modes, 2-player battles, and rhythm-based fights like Stronger Than You.

What other boss fights can I play?

Beyond Bad Time Simulator battles, we feature the complete Undertale boss collection and Deltarune encounters. Each boss has unique mechanics—from Undyne's spear patterns to Jevil's chaotic attacks, plus creative crossover battles.

How do the difficulty options work?

Choose your challenge level: Normal mode for the authentic Bad Time Simulator experience, or practice modes with infinite health to learn Bad Time Simulator patterns. Advanced players can try endless modes for ultimate endurance tests.

Can I play Bad Time Simulator unblocked?

Yes! bad-time-simulator.com is fully accessible without any restrictions or limitations. You can enjoy the complete experience online whether at home, school, or work.

Is there a mobile version available?

Yes, the game is playable on mobile devices! Touch-based controls will appear on your screen (press and hold to move in any direction, with A button for confirmation and B button for going back). However, the experience isn't ideal for this precision-demanding game. For the best Bad Time Simulator experience with optimal control and responsiveness, we still recommend playing on a desktop or laptop with a keyboard.

Comments

Charles

1 day ago

Yawn, this is too easy. I can no hit this like it's no big deal

sans

1 month ago

hi bro

unstar25 days ago

papuyrus16 days ago

WHY ARE YOU HERE? YOU SHOULD BE AT YOUR POST IN SNOWDIN! NOT PLAYING WITH YOURSELF!

StrongFish9112 days ago

Um, Papyrus? That sounds a little weird.

papyrus1 day ago

THAT'S NOT WHAT I MEANT!!! Ugh, just come back to Snowdin! Undyne's worried about you fighting yourself endlessly!

StrongFish911 minute ago

Yeah, Paps is right. SO GET YOUR LAZY BUTT OFF THE COMPUTER OR I'LL COME OVER THERE AND DRAG YOU OUT OF THE HOUSE MYSELF!!!!!!!!

StrongFish91just now

Uh, after a put on a coat.

StrongFish91just now

Uh, after I put on a coat.

sans

1 month ago

StrongFish912 days ago

SANS!!!!!!! WHY AREN'T YOU AT YOUR SENTRY STATION!!!!!!!! GET! BACK!!! TO!!!!! WORK!!!!!!!!!!!! Also Papyrus got his head stuck in the oven again and he's freaking out.

阿

阿萨大

3 months ago

Ryan

3 months ago

I can't believe I pass the Practise mode!

Comments

Charles

1 day ago

Yawn, this is too easy. I can no hit this like it's no big deal

sans

1 month ago

hi bro

unstar25 days ago

papuyrus16 days ago

WHY ARE YOU HERE? YOU SHOULD BE AT YOUR POST IN SNOWDIN! NOT PLAYING WITH YOURSELF!

StrongFish9112 days ago

Um, Papyrus? That sounds a little weird.

papyrus1 day ago

THAT'S NOT WHAT I MEANT!!! Ugh, just come back to Snowdin! Undyne's worried about you fighting yourself endlessly!

StrongFish911 minute ago

Yeah, Paps is right. SO GET YOUR LAZY BUTT OFF THE COMPUTER OR I'LL COME OVER THERE AND DRAG YOU OUT OF THE HOUSE MYSELF!!!!!!!!

StrongFish91just now

Uh, after a put on a coat.

StrongFish91just now

Uh, after I put on a coat.

sans

1 month ago

StrongFish912 days ago

SANS!!!!!!! WHY AREN'T YOU AT YOUR SENTRY STATION!!!!!!!! GET! BACK!!! TO!!!!! WORK!!!!!!!!!!!! Also Papyrus got his head stuck in the oven again and he's freaking out.

阿

阿萨大

3 months ago

Ryan

3 months ago

I can't believe I pass the Practise mode!

Ready for the Challenge?

Play Bad Time Simulator Now!

Bad Time Simulator

Bad Time Simulator | Sans Fight & Undertale Boss Battles

Game Overview

What is Bad Time Simulator?

How to Play Bad Time Simulator

FAQ

What does bad-time-simulator.com offer?

What Bad Time Simulator versions are available?

What other boss fights can I play?

How do the difficulty options work?

Can I play Bad Time Simulator unblocked?

Is there a mobile version available?

Ready for the Challenge?