How to Play Bad Time Simulator
Bad Time Simulator is a browser-based Sans Fight Simulator that recreates the Sans boss battle from Undertale. Play the encounter here, or practise individual patterns before attempting a full run. This guide covers the controls, training modes, blue-soul jumps, and common trouble spots such as moving platforms and Gaster Blasters. Prefer party-based battles? The Deltarune Fight Simulator lets you switch from Sans attack patterns to Dark World encounters.
Click Play and wait for the game menu. Use the arrow keys to select a mode and Z or Enter to confirm. Start with Practice to learn the sequence; choose Normal when you want to attempt the fight with its battle-menu turns. If the menu does not respond, click inside the game window.
Your heart is the soul you control. When it is red, move freely around the box to avoid attacks. When it turns blue, gravity pulls it toward a surface: jump away from that surface to clear obstacles. Watch for changes in gravity rather than assuming that every jump uses the Up key.
Bad Time Simulator Controls
| Key | Action |
|---|---|
| Arrow keys | Move the heart / navigate menus |
| W / A / S / D | Alternative directional controls: up / left / down / right |
| Z / Enter | Confirm a menu selection or battle-menu action |
| X / Shift | Cancel where supported; return to the main menu from Single Attack |
| Up arrow / W | Jump with the blue soul when gravity pulls downward; use the direction opposite gravity when it changes |
These bindings apply to the jcw87 build embedded here, not every Sans remix. Release the jump direction sooner for a lower hop, and release then press again for the next jump. Click the game after using Search to return keyboard control to it.
What Is Bad Time Simulator?
Created by jcw87, Bad Time Simulator is a fan-made Sans Fight Simulator recreating the Sans boss encounter from Undertale by Toby Fox. It separates the battle from the rest of the game, so you can practise its attack patterns without replaying the story to reach Sans.
It is not an exact substitute for the original encounter. The author's project notes identify a potentially inaccurate heart hitbox, missing Sans dialogue, and different platform motion in the sans_platforms4 and sans_platforms4hard attacks. Those platforms begin at full speed instead of accelerating, which can affect attempts to dodge bones without jumping.
Game Modes
- Normal: play the simulator's standard fight sequence, including battle-menu turns between attacks. Use it to put the patterns together into a complete attempt, rather than repeatedly practising one section.
- Practice: work through attacks with health restored at the start of each pattern. The game checks your performance: a successful attempt advances, while taking too much damage makes you repeat that pattern. Choose this when you are still learning the sequence. It is not simply Normal with infinite health.
- Single Attack: select a particular attack from a list instead of reaching it through earlier rounds. Use it when one pattern keeps ending your run, such as a platform section or the final blasters. Press X or Shift to return to the main menu.
- Endless: choose Phase 1 or Phase 2 and practise a continuing stream of that phase's attacks. It is useful for linking dodges together without the usual battle-menu breaks; it is not a selector for one exact attack.
The menu also includes Custom Attack. This loads user-made attacks described in CSV files using the original project's scripting format. You do not need a custom file to play the built-in modes.
Tips for Beating Sans
- Match the mode to the mistake. If one late attack ends every run, select it in Single Attack instead of replaying the opening. Once you can get through it reliably, return to Normal to practise entering it after the preceding attack.
- Use short hops for low bone gaps. In blue-soul sections, holding the jump direction longer makes a different arc from tapping and releasing it. If a high jump sends you into an overhead obstacle, release earlier rather than repeating the same full-height jump.
- Reset your jump input after landing. Release and press the jump direction again for the next hop. Holding it continuously is not a reliable substitute for timing each jump over successive bones.
- Recheck gravity after a slam. When the blue soul is pulled toward a wall or ceiling, pressing Up out of habit can send the wrong input. Identify the surface pulling you in and jump in the opposite direction.
- Learn this simulator's moving platforms separately. If platform timing learned in Undertale feels wrong, practise the named platform attacks here. Two documented patterns start their platforms at full speed; do not assume that a no-jump dodge from the original transfers unchanged.
- Drill the rotating Gaster Blasters as a route. In Single Attack, practise a continuous circular path through the rotating pattern instead of crossing the middle in a last-second escape. Adjust your distance from the centre between attempts; there is no guaranteed safe spot to stand still.
- Use Practice failures to isolate one correction. A repeated pattern means you did not meet its damage check, not that the mode is stuck. On the next attempt, change one detail, such as jump release timing or where you begin moving, before trying a different route.
FAQ
Is this the full Sans fight or the full Undertale game?
Normal offers the simulator's full fight sequence, rather than just one selected attack. It is not the full Undertale game: exploration, the story leading to Sans, and his original dialogue are not reproduced here.
Can I play on a phone?
This build includes touch controls, but the original game also warns against playing on mobile. A desktop or laptop keyboard is the recommended option for precise movement. Touch controls being present does not guarantee comfortable play or compatibility with every phone and browser.
Why is the game not loading?
Click Play first: the game loads only after you start it. Allow the initial resources to finish downloading. If it remains stuck, use Restart to reload the game, then try refreshing the page. If the problem continues, check your connection and try another browser; a stalled loader alone does not identify the cause.
Why are my keyboard controls not working?
Click inside the game, especially after typing in Search or switching tabs. Try the arrow keys and Z or Enter at the menu. If text is still appearing in a webpage input, the keyboard is controlling that input rather than the game.
Does Bad Time Simulator have sound?
Yes, this version includes music and sound effects. If it is silent, interact with the game first, then check browser-tab muting and your device's audio output and volume. There is no separate website volume slider. Restart reloads the game and also restarts your current attempt.
Is it harder than the original Sans fight?
There is no reliable single difficulty rating that applies to everyone. The simulator has documented hitbox and platform differences, and players report different experiences. Treat it as pattern practice, not proof that a dodge will behave identically in Undertale.
Why does Practice keep repeating the same attack?
Practice advances when you pass the current pattern's damage check. If you take too much damage, it repeats that pattern with restored health. To choose a different attack directly, leave Practice and use Single Attack instead.
Does this version include Last Breath or other Sans mods?
The embedded game is jcw87's Sans fight simulator, not a collection of other fan battles. Names such as Last Breath refer to other projects or adaptations. The Custom Attack option loads compatible attack files; it does not automatically add those games.
