Roaring Knight Fight

Deltarune Fight Simulator

The Roaring Knight is the fight this site is built around. The other bosses are here too, each one a fan build you start with Play.

These are the fights on Roaring Knight Fight. Deltarune Fight is the sister site, with its own builds. Open a card, press Play, then click the game so the keyboard works.

The fights

Screenshot from Gangstermango's Roaring Knight remake, with the party facing the Knight.

Roaring Knight Fight Simulator The main fight on this site. The sword tunnel is the deadliest stretch.

The opening of Bad_Time_Trio1's Roaring Knight fight, with Kris, Susie, and Ralsei facing the Knight.

Black Knife Simulator The same Knight. You pick who wears the Shadow Mantle.

Title card for S00TF00T's Sans fight simulator, with a winking Sans on a black field.

Sans Fight Simulator The other Genocide boss. He hits first, and the spare is a trap.

Screenshot from taiseitaisei's English Jevil fight, with the party and the line LET THE GAMES BEGIN.

Jevil Fight Simulator A Shadow Crystal boss. Stay centred, or tire him out and Pacify.

The packaged battle's first picture, party on the left and the wired salesman on the right.

Spamton NEO Fight Simulator Yellow heart. Stay on the left and shoot.

Screenshot from pp920921's Omega Flowey fight, showing the television face, eyes, and vines.

Omega Flowey Fight Simulator Not a turn menu. Dodge, then find ACT when a SOUL warns you.

Title card from RatchetJobaria's Undertale Yellow Meta Flowey fight, a dark flower above the words META FLOWEY FIGHT.

Undertale Yellow Flowey Fight Simulator Undertale Yellow's flower. Shoot the red weak points.

Susie facing Gerson in littlewill565's Hammer of Justice fight, with the TP bar and the line about the bell of justice.

Gerson Fight Simulator Chapter 4 secret. Green shield. About 12 of 21 turns.

The heroine appears in tripoid's Undyne the Undying fight, with Fight, Act, Item, and Mercy along the bottom.

Undyne the Undying Fight Simulator A full Genocide spear fight. Yellow arrows flip.

Asriel in the God of Hyperdeath form in tripoid's Asriel Dreemurr fight, with the line that the true final battle was finally beginning.

Asriel Dreemurr Fight Simulator True Pacifist finale. Stars, sabers, then SAVE.

Four Gaster Blasters firing an X of white beams through the battle box in Bad Time Simulator, with Sans standing above it.

Bad Time Simulator jcw87's Genocide Sans clone. KARMA, blasters, Practice mode.

Asgore greyed out behind the battle box while a ring of white fireballs closes on the red heart, with FIGHT, ACT, and ITEM below and no MERCY button.

Asgore Fight Simulator The king at the barrier. Fire, trident, no MERCY.

Mettaton EX posing above a square battle box while white boxes fall toward the yellow heart, HP 15 of 20 in the corner.

Mettaton EX Fight Simulator Yellow SOUL. Shoot boxes and bombs, dodge the legs.

The Roaring Knight over a bullet box, with Kris, Susie, and Ralsei in the command menu of phychosis3's Kaizo Knight fight.

Kaizo Knight Fight A harder Knight. Not the Shadow Mantle picker.

Pick a fight

The Knight pages are the Chapter 3–4 sword fight. Roaring Knight is the main remake. Black Knife is the same boss, and it asks who wears the Shadow Mantle before the swings start. The sword tunnel is the deadliest stretch in that battle, because it gives almost no invincibility. You can only win it by attacking.

Jevil, Spamton NEO, and Gerson are the Shadow Crystal bosses on this list. Gerson is the Chapter 4 one, and the fight is optional. His build here covers about 12 of the real fight's 21 turns. Jevil can be spared once Tiredness hits 9, with Ralsei's Pacify. Spamton's peaceful route is SnapAll: Kris and Susie snap while Ralsei heals, and that turn adds 7% mercy.

Undyne the Undying is the third boss of Undertale's Genocide Route. Sans is the other Genocide boss. Omega Flowey is the fight that is not a turn menu. Undertale Yellow Flowey is a different flower, the Neutral finale inside Flowey's mind, and the build here is the petal phase.

What you are dodging

Green shield: Gerson and Undyne. You stay in the centre and turn a shield toward the next spear. Gerson adds diagonals partway through attack 5. Undyne's yellow arrows flip to the opposite side.
Yellow heart: Spamton NEO and Undertale Yellow Flowey. Spamton wants you on the far left, shooting right. Yellow Flowey wants the red weak points, and X dashes in that project.
Sans starts on a blue heart, so you jump. Most hits apply KARMA, a drain after the hit. Accepting his spare fills the board. Only FIGHT moves that battle.
Omega Flowey never settles into a normal menu. Step out of the flashing ring, get off the vine lines, and press ACT when a SOUL warning hides the button. After all six SOULs you can take about 13 hits.
If a Knight pattern is what you came for, the sword tunnel is the one to practice. Roaring, the full-screen attack, ignores defense. One hit after the Knight drops its guard ends it.
Undyne's spinning rings of eight spears are the attack a no-hit guide calls her hardest. Players on that project talked about the clear taking a long time.

Gerson and Undyne need a keyboard. Arrows, Z, and, for Gerson, C to skip the opening. Undyne uses X to cancel. The Knight remake asks PC or Mobile, and a keyboard is still the reliable way through it.

FAQ

What is this Deltarune fight simulator?

It is a list of the boss fights on Roaring Knight Fight. The Roaring Knight is the main one. The other cards are Black Knife, Sans, Jevil, Spamton NEO, Omega Flowey, Undertale Yellow Flowey, Gerson, Undyne the Undying, Asriel Dreemurr, Bad Time Simulator, Asgore, Mettaton EX, and Kaizo Knight. Each card opens that fight. Press Play on the fight page and the battle loads in the browser.

Which fight should I open first?

Open the Roaring Knight if you want the fight this site is built around. Open Jevil or Spamton NEO if you want a Shadow Crystal boss you can spare. Open Gerson or Undyne if you want a green shield. Gerson's build here is about 12 of the real fight's 21 turns. Undyne's is a full fight. Open Asriel for the True Pacifist finale. Open Bad Time Simulator to drill the Genocide Sans battle.

Is this the same site as Deltarune Fight?

No. Deltarune Fight is a sister site with its own fan builds. The list here is the fights on Roaring Knight Fight, with the Roaring Knight first.

Can I play these fights on a phone?

Bring a keyboard for Gerson, Undyne, and Asriel. Their fights use arrow keys, and a touch screen does not cover them. The other fight pages list their own keys. The Knight remake asks PC or Mobile at the start, and a keyboard is still the reliable way to play it.

Is the Deltarune fight simulator free?

Yes. It's free to play in your browser. Press Play on a fight and it loads. There is no installer.