DeltaruneFight

Deltarune Fight Simulator

Bad Time Simulator

Next boss

SansScratch take on the same duel, Japanese text.UndyneThe other Genocide wall, spears this time.AsrielRainbow finale from the True Pacifist route.

jcw87's rebuild of the last-corridor duel, KARMA bar and Gaster Blasters included. Hit Play, pick a mode with the arrows, and lock it in with Z or Enter. Expect to lose the first few runs in seconds.

Bad Time Simulator gameplay: Sans, Gaster Blasters, and a bone-filled bullet box over the CHARA LV 19 HUD.

Picking your bad time

Five choices wait at launch, from a full Normal run down to a Custom attack sandbox. Up and Down move the heart cursor, and it wraps from the top row to the bottom one.

Normal is the straight duel, and dying kicks you back to that menu. Practice flashes FAILURE in red, refills HP, and lets Sans ask ready? again, so you can drill the opener without sitting through the speech. Single attack is the pick for grinding one pattern you keep dying to.

The HUD copies the Genocide run: CHARA, LV 19, and a 92 HP bar with KR beside it. If your browser has WebGL switched off, Sans breaks character to tell you some effects will not render.

The Select your bad time list in white on black: Normal, Practice, Endless, Single attack, and Custom attack, with a red heart beside Practice.
Practice mode after a death: red FAILURE text in the corner, Sans asking ready?, and the HP bar refilled to 92/92.

Spoilers

Surviving the opener

Sans swings first, and he swings hard. Your heart turns blue and gets slammed to the floor of the box, where a red strip warns you that bones are about to rise; jump right away. Then the heart flips red for a wall of bones with a crooked gap you have to follow.

Four rounds of Gaster Blasters close it out: one set covering the sides, one firing corner to corner in an X, a repeat of the sides, and two huge skulls whose beams leave only the top and bottom edges safe. Every skull pops in and opens its jaw before the beam fires, so move the moment you see it.

KARMA is why a graze hurts so much. Each hit stacks KR, which keeps chewing HP after the bone is gone, painted magenta on the bar. Get out of a pattern instead of tanking it, and if you are healing in the full duel, wait for the drain to stop first.

Sans flanked by four Gaster Blaster skulls while a red heart threads a column of white bones, HP bar split yellow, magenta, and red.

Endless, tougher files, and your own CSV patterns

No hard mode button exists in jcw87's menu. Endless is the real stress test since the waves never stop, and the stock attack files already include tougher twins such as sans_platforms4hard, sans_bonegap1fast, and sans_platformblasterfast.

Pick Custom attack to load a pattern you scripted yourself. jcw87's GitHub documentation explains the format: every row of the .csv starts with a wait time in seconds, then names a function, then lists whatever arguments it takes. A spreadsheet export is the suggested workflow, and forgetting EndAttack leaves the attack running forever.

Bad Time or our Sans Fight Simulator?

Both recreate the same Judgment Hall showdown from the Genocide Route, where Sans has 1 HP, dodges your swings, and drains you with KR while Megalovania plays. Each was coded by somebody else.

Our Sans Fight Simulator is a Scratch project by sugiharu1012 with Japanese menus and a fight that stops partway. Bad Time is jcw87's English rebuild in Construct 2, with the mode list, Practice retries, and single-attack drills on top. The roaringknightfight.com copy of Bad Time Simulator runs the same jcw87 build.

FAQ

Is there a Bad Time Simulator hard mode or custom attack editor?

No hard toggle, but Endless plus the hard and fast attack files fill that role. Scripting your own waves means following the CSV format jcw87 documents on GitHub.

Which buttons move the heart?

Arrow keys slide the cursor on the mode list and steer your heart in the box. Z or Enter selects a mode and moves Sans's speech bubbles along. Stuck keys usually mean focus is elsewhere; tap the canvas and try again.

Does it cost anything?

Yes. No account, no download, no paywall. Press Play and the game streams straight into your tab.

Can I play it unblocked at school?

It runs in a normal browser tab with nothing to install, served from gamebox.bvnplay.online after you press Play. A school or work filter can still block either domain, so no promises there.

How is it different from the Sans Fight Simulator on deltarunefight.com?

Our Sans Fight Simulator runs sugiharu1012's unfinished Scratch battle with Japanese text. Bad Time is jcw87's English Construct 2 build with a mode menu, Practice retries, and the full Gaster Blaster opener.

Does it work on a phone?

The export ships an on-screen pad, but dodging bone gaps by thumb is rough. A physical keyboard is the way to go, and a Chromebook with keys is fine.

Credits

Bad Time Simulator (Sans Fight) was built by jcw87 in Construct 2; the original lives at jcw87.github.io/c2-sans-fight. All characters and music here remain the property of their creator.

No reuse license is declared in jcw87's current repository. Attribution does not authorize redistribution or commercial use; permission and third-party asset rights remain unverified. UNDERTALE is © Toby Fox. Unofficial fan site.

Game authors who want a game removed or credited differently can email support@deltarunefight.com.

Sources