How to Play Bad Time Simulator
Bad Time Simulator is a free fan-made browser game that recreates the legendary Sans boss fight from Undertale. If you've ever wanted to experience that heart-pounding dodge-fest without owning the original game, this is the place. This guide covers everything — from basic controls to surviving every attack pattern.
Getting Started
Step 1 – Open the Game
Navigate to the game page. The title screen loads immediately — no plugins, no downloads. Press Z or Enter to begin.
Step 2 – Read Sans's Dialogue
Sans delivers his iconic pre-fight taunts one line at a time. Press Z to advance, or press Z while text is still typing to instantly reveal the full line. After the last line the battle begins.
💡 Tip: First-time players should read all dialogue lines — they set the tone and give you a moment to settle in before the fight.
Controls Reference
Keyboard
- W A S D or Arrow Keys — Move the soul
- Z / Enter — Confirm selection
- X / Esc — Cancel / go back
- M — Toggle music on/off
Mobile / Touch
On touch devices, a virtual D-pad appears automatically in the bottom-left corner. Use Z and X buttons on the right to confirm or cancel. The game is fully playable without a keyboard.
The Battle System – Turn Structure
Bad Time Simulator uses the classic Undertale turn-based format split into two phases that alternate continuously:
- Player Turn — Choose an action: FIGHT, ACT, ITEM, or MERCY.
- Enemy Turn — Your soul is placed in the battle box. Dodge incoming attacks until the turn timer expires.
Turns get progressively shorter and attacks become faster with each round. There is no true win condition — the goal is to survive as many phases as possible.
Player Turn – Choosing Actions
Use ← → to cycle between the four options, then press Z to confirm:
- FIGHT — Opens a timing meter. Hit Z when the indicator is near the centre for the best rating. Note: Sans dodges every attack — no real damage is dealt.
- ACT — Skips directly to the enemy turn.
- ITEM — Skips to the enemy turn.
- MERCY — Also skips to the enemy turn (Sans ignores it).
⚠ Note: This is a fan game — you cannot actually defeat Sans. The fight loops indefinitely with increasing difficulty.
All 6 Attack Patterns Explained
The game cycles through six distinct attack types. Understanding each one is the key to surviving longer.
1 — Bone Rain
Bones fall vertically from the top of the battle box. Move left and right to dodge the gaps. Bone count increases each cycle.
2 — Bone Sweep
A wide horizontal bone sweeps across from one side. Watch the direction it enters and move to the opposite half of the box.
3 — Gaster Blasters
Skull-shaped lasers appear outside the box, charge with a red warning line, then fire a beam. Move out of the beam path before it fires.
4 — Bone Wall
A solid wall of bones sweeps across with one gap. Identify the gap position quickly and move into it before the wall reaches you.
5 — Blue Soul Mode
Your soul turns blue and gravity applies. Blue bones only hurt you if you are moving — stand still when they pass through.
6 — Diagonal Bones
Bones enter from random edges at 45° angles. Move fluidly and avoid getting cornered — keep near the centre of the box.
Health, KR, and the HP Bar
Your soul starts with 92 HP. Each hit reduces HP based on the attack type — Gaster Blasters deal more damage than standard bones. The HP bar is displayed at the bottom of the screen at all times.
Karmic Retribution (KR) is an additional damage effect applied by Gaster Blasters. It appears as an orange segment on the HP bar that slowly drains your health over time even after the hit. Move carefully and avoid Blasters to minimise KR accumulation.
Pro Tips – Surviving Longer
- Stay near the centre of the battle box — you have maximum escape room in all directions.
- Gaster Blasters: Watch the red dashed warning line during the charge phase. Move out of line before the beam fires, not after.
- Blue Soul: Hop to a safe height, then stop moving entirely. Only jump again when the next blue bone approaches.
- Bone Walls: Look for the gap as soon as bones appear on screen — you have about one second to position.
- Diagonal: Don't panic — diagonal bones are sparse. Gentle, slow movements beat frantic dodging.
- Invincibility frames: After taking a hit you get ~0.65 s of invincibility (your soul blinks). Use this to move through danger you cannot avoid.
- Music toggle: Press M to mute the background music if you need to focus. Sound effects remain active.
💡 Advanced tip: In Bone Rain, instead of chasing gaps reactively, pick a lane and only move when a bone is directly above you. Constant movement wastes your reaction time.
Frequently Asked Questions
Can I actually beat this game?
No — this fan game loops indefinitely. There is no final win screen. The goal is simply to survive as many attack phases as possible and beat your own record.
Does the game save my progress?
No save system is implemented. Your phase count is displayed on the Game Over screen, but it resets when you close the browser tab.
Is this the original Undertale game?
No. This is an unofficial fan recreation made independently. The original Undertale game was created by Toby Fox and is available on Steam and other platforms. This project is not affiliated with Toby Fox in any way.
Why does the music sound different from the real Megalovania?
The music in this fan game is a procedurally generated chiptune inspired by Megalovania, built entirely with the Web Audio API — no audio files are used. It is not a recording of the original song.
The game runs slowly on my device. How do I fix it?
Try closing other browser tabs and applications. The game runs at 60 fps using the Canvas API — modern devices handle it easily. On older phones, reducing background processes helps significantly.