Deltarune Fight Simulator

Susie and the hammer, a partial browser duel

Next boss

Play leaves a still picture until you ask for the frame. After that, Susie is alone with an axe, the real duel keeps going long after this build stops, and a touchscreen never gets a turn.

Gerson gameplay framed as a Deltarune Fight Simulator card: Susie and the Hammer of Justice in a green study.

What the frame does once you click

littlewill565's instructions keep the duel at twelve turns for now, interaction on the arrows and on Z, the cutscene dismissed with C, and Rude Buster fired by mashing Z, after a patch that calmed stutter coming from the health bar.

The packaged boot still opens mid-argument in the shop, the complaint being that the axe has to be paid for, and C is printed on the picture as the way out. With that gone, Susie is the only body left, command row and TP bar included, and the locked-colour patterns show up along with bells ringing in justice plus the warning that this colour means you cannot bolt.

Player comments split: diagonals get called hard or broken, and one run jammed while the bells were still on screen, while others call the recreation really good, which is as honest as the praise needs to be. A louder fan build exists, but it leaves debug monitors up, so the picture here stays on project 1198053915.

A curtained study. The prompt says C to skip cutscene, and Susie's dialogue box is still typing.
Susie with an axe faces the Hammer of Justice across an anvil, red curtains and bookshelves behind them.

Spoilers

Rewards, the Study door, then the two Gersons

What you carry out is four Magic Susie keeps, BetterHeal standing in for OKHeal at a lower TP price, the JusticeAxe, and his Shadow Crystal, though that pile is the prize list and not the last picture. The closing image is beard hairs clipped after a healing shot fired above his head. Fall here and you are put back on the walk you left, because a loss in this encounter never becomes a game over.

Alvin's father had already died: Gerson Boom, a Hometown writer who left history for the fantasy series Lord of the Hammer. A hammer left dusty is the Chapter 4 prop that lets a Darkner wear his face. Inside the Dark Sanctuary the only name he answers to is Old Man, and the hours there are lessons for Susie.

Read the wiki infobox rather than a check line for the figures: 1350 HP, defense listed as 0 on account of every swing missing, attack that opens at 15 and rises as Susie's remaining HP drops. Chapter 4 puts its Shadow Crystal encounter in the Study, and the shape you fight there goes by 正義の鉄槌, the hammer English calls Hammer of Justice, while the music motif is just the name Gerson.

IGN's route to the door is the ClaimbClaws, three stretches of piano, and then the golden piano, which opens onto the JusticeAxe. He quotes a price of $999,999,999 and calls that already reduced, then says one cut hair would settle it. She never lands the cut, he changes, and the whole encounter can be skipped. Go in before you climb the tower that begins the Dark Sanctuary: that climb pushes the plot forward and removes the door.

Kris and Ralsei never join the party. Even so, Susie still turns to Kris and asks for help once the colour locks. Between boards he walks her through the Lord of the Hammer chapters, her wish is a story with no last page, and his reply is hope's white pen.

Two lines worth hearing in his voice: "Can you hear its song, singing from the deep…? That… is the ringing… of the Hammer of Justice!" and "As long as you're GREEN, you can't run away! Unless you FACE DANGER HEAD ON… These bullets will do you in!"

Keep the turtles apart: the notebook was sold by Undertale's Waterfall shopkeeper, and the man waiting in the Study is not that shopkeeper. Players still pack the notebook against Undyne the Undying because the extra invincibility frames matter, and both duels pin the heart. Secret bosses elsewhere on this site are Spamton NEO and Jevil. littlewill565's project is also up on roaringknightfight.com.

Susie at 230 HP faces the Hammer of Justice. A vertical TP bar reads 24 percent beside a pink HP bar.

Spoilers

Stars, shells, and the swings that flip the colour

Chapter 4's hammer runs twenty-one attacks while littlewill565's frame reaches about twelve, and the only controls are a keyboard's arrows for the axe and the heart, Z to confirm, C to dump the opener, plus a Z mash when Rude Buster should fire.

Clearing the real duel means living through the 21st swing, and a star count of 84 or higher leaves him impressed enough to call that swing early. Prices on the late survivals, counted backward, are 20 stars for attack 20, 24 for 19, 24 for 18, and 30 for 17, while OKHeal pays 9, a knocked-back reflection of Rude Buster pays 8, a missed deflect pays 6, and FIGHT pays 4 stars together with 24% TP, so a swing still advances him even when the blow never lands. DEFEND is the thin bargain: 16% TP loaded up front, about a third shaved off the incoming hit, and a star gain of zero.

  • The locked colour pins the heart at mid-board and the axe guards whichever side you are holding, four directions first, then an eight-sided board from halfway through attack 5, where a diagonal means two arrow keys together.
  • A block you simply hold is 0.5% TP, flicking the axe over or tapping that same direction again as the spear connects is 1% TP, and this colour gives no graze.
  • Spears are drawn as yellow arrows, the one about to land picks up a red body and a yellow outline so you follow that red one, a direction written in the attack list is the side you guard rather than the spear's flight path, and the waves mostly repeat so they can be learned.
  • Shells that show a colour come back and need several blocks, cyan shells spin and the rebound is a quarter-turn counter-clockwise, and larger shells travel more slowly.
  • A hammer that lands, caught or connected, paints the heart red.
  • Attacks 1 and 2 exist only on a first playthrough, attacks 1 through 5 are arrows that start leisurely and then get quicker, and the eight-way board shows up during the fifth.
  • Attacks 6, 7, and 8 are the opening hammer set: leave the middle lane on the sixth slash, meet a shell trailing stars that gets spiked down the center and then a rain of stars on the seventh, and on the eighth a tilted floor, hammers thrown in arcs, and one huge hammer down the middle.
  • Attacks 9 through 11 go back to the locked colour, arrows plus the earliest shells, attack 14 replays the tilt from attack 8, and attacks 15 and 16 fold spinning shells in with arrows and a hammer.
  • Attack 12 starts with a hammer that shoves you left, then cuts the middle lane, the right, and the left, two copies of him acting as a feint before a third follows, while attack 13 squashes the board until it is wide and thin and the cuts leave only a small pocket.
  • If you count the late volleys you can tell the storms apart: circles of 5, then 5, then 11, then 30, then 32 arrows that arrive at random and speed up, then 48 that stay slow and packed, covering attacks 17 through 19, with a shell-heavy mix sitting on attack 20.
  • The last swing wants a loop around the middle of the board: four shells, a fast shell among them, a hammer after the shells, and cuts that travel counter-clockwise.
  • He sends Rude Buster back at you, and knocking that reflection into him both staggers him and keeps the damage off Susie, which in this Scratch build is what the Z mash is for.
  • A connecting hit costs about a third of whatever HP Susie still has, and at least 12 before reductions, he confiscates items so OKHeal is the heal you can count on, each cast strengthens it a little, that gain survives a loss, and losing the real duel puts you back in the overworld rather than on a game-over screen.

FAQ

Which keys does littlewill565's hammer build actually read?

Arrows aim the axe and step the heart, Z confirms a menu choice, C throws away the opener, and Rude Buster is a mash on Z, which is how the Scratch instructions describe it. No touch pad was added.

Can a handset finish the Study duel, or only a Chromebook with keys?

A handset cannot, because nothing on the glass stands in for those keys. A Chromebook can, once a physical keyboard is attached and you have clicked the running picture so the presses land inside it.

When is gamebox.bvnplay.online asked for the hammer file?

Merely opening the address fetches nothing, the Study staying a poster until Play sends the request to gamebox.bvnplay.online, and a school or office filter can still refuse deltarunefight.com or that game host.

Does Hammer of Justice HIGH QUALITY charge before it starts?

littlewill565 published it free on Scratch, with no account to make, and Play opens that project in the browser rather than handing you a file to install.

Does littlewill565 include every one of the twenty-one hammer attacks?

No. The Scratch instructions say twelve turns so far, while Hammer of Justice in Chapter 4 has twenty-one attacks, so expect a partial duel, keys only, C for the cutscene, and a Z mash for Rude Buster.

If Susie picks FIGHT, does the real hammer duel move forward?

In the real battle, yes: FIGHT is 4 stars plus 24% TP, and the wiki counts that as progress even though he dodges the swing. You still have to live through attack 21, and a high star total is what brings that attack early.

Credits

littlewill565 wrote Hammer of Justice HIGH QUALITY as an original Scratch project. By 11 October 2026 the counters read 1,414 views, 63 loves, and 54 favorites, the share date being 21 July 2025 and the last edit 29 September 2026, with the author's cap at twelve turns, interaction on arrows and Z, C dismissing the cutscene, Rude Buster on a Z mash, and a health-bar patch that stopped the stutter.

The original project and author are credited here. Reuse depends on the license or permission applicable to the specific build, including third-party art and music; credit alone is not permission. This site does not grant a license to those works. UNDERTALE and DELTARUNE are © Toby Fox.

Browser packaging uses TurboWarp, click-to-start, a restart/status bridge, and a local browser-storage provider for Scratch cloud variables. The packaged copy can behave differently from the original Scratch page.

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

Sources