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Mod that adds difficulty options to Deltarune. Make the game easy, hard, or nightmare! ( or no-hit! )

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Custom Difficulty Mod for DELTARUNE

Difficulty options for DELTARUNE. Make the game easy, hard, or nightmare! ( or no-hit! )

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Latest release

What you can change

  • Presets — Select from various difficulty presets
    • Easy -50% damage, +50% i-frames
    • Normal Standard Deltarune experience
    • Hard +50% damage, -20% i-frames, -10% enemy cooldowns
    • Nightmare +100% increased damage, -35% i-frames, -20% enemy cooldowns
    • Nightmare-EX +150% damage, -50% i-frames, -30% enemy cooldowns
    • Nightmare-Neo NIGHTMARE-EX with -50% battle rewards, and no passive regen/revive for downed characters
    • No-Hit Infinite damage to every party member

Battle

  • Damage Multi — multiply all incoming damage by this value

    • Attacks that are scripted to leave a character at 1 HP, or other threshold, still do so.
    • For attacks that deal damage as a percentage of the current HP, instead uses exponential logic to determine damage scaling. e.g. An attack that normally does 50% of your HP in vanilla, instead does 70.7% with double damage, and 25% with half damage. The calculation is thus: dmgratio = vanilladmgratio^(1/dmgmulti).
    • For any damage over time effects, either tick faster, apply more damage, or combination of both - where appropriate - proportionate with the multiplier that has been set.

  • Hit.All — when switched on, hits that target a single character instead hits the entire party

    • Additionally, attacks that adjust their damage for certain characters, no longer do so.
    • For no-hit runs, combine this setting with Damage Multi=INF.

  • I-Frames — multiply the number of i-frames received after damage by this value

  • Enemy Cooldowns — multiplier for the cooldown between enemy attacks & bullet patterns

    • Heavily scripted attacks/encounters may not change much if at all.
    • A few tweaks have been made to some attacks:
      • Reduce random placement of heart shapers (Head Hathy) at lower cooldowns as the attack can trap you.
      • Cap timer reduction for wave chain (Spade King) as it becomes a solid wall quite quickly.
      • Shorten tails for chain of hell (Spade King's chain bullets) at lower cooldowns as the attack can trap you.
      • Ensure Queen's leg stomp attack waits for an available slot before spawning a leg, instead of flooding the box.
      • Chapter 3's super boss' full-screen attack is hard capped at >25% cooldown to prevent crashing.
      • Winglade's aim attack is hard capped at >50% cooldown to prevent it from getting stuck.

  • Battle Rewards — multiply post-battle rewards by this value

Down

  • Down Deficit — when a party member is downed, their HP is set to -50% max HP; this option overrides that
  • Downed Regen — when downed, party members regen 12.5% max HP every turn; this option overrides that
  • Victory Res — when a battle is won, all downed party members are healed up to 12.5% max HP; this option overrides that
    • OFF: Can also be switched off entirely by reducing past 0%.

Player

  • Damage — multiply outgoing damage by this value
  • Healing — multiply healing from spells & actions by this value
  • TP Gain — multiply TP gain from all sources (except item use) by this value
  • Mercy — multiply mercy build-up by this value
CHAPTER 3 SPOILERS...

Battle

  • Gameboard Dmg X — multiplier for the incoming damage in the chapter 3 game boards

    • Only shows up in the menu in chapter 3.
    • INHERIT - Can be set to inherit from the 'Damage Multi' setting by reducing past 0%.
    • Attacks that are scripted to leave a character at 1 HP, or other threshold, still do so.

  • Gmbrd Enemy CDs — multiplier for the enemy attack cooldowns in the chapter 3 game boards

    • Only shows up in the menu in chapter 3.
    • INHERIT - Can be set to inherit from the 'Enemy Cooldowns' setting by reducing past 0%.

Player

  • Gmbrd Damage — multiplier for outgoing damage in the chapter 3 game boards

    • Only shows up in the menu in chapter 3.
    • INHERIT - Can be set to inherit from the 'Damage' setting by reducing past 0%.

  • Gmbrd Healing — multiplier for healing from collecting candy in the chapter 3 game boards

    • Only shows up in the menu in chapter 3.
    • INHERIT - Can be set to inherit from the 'Healing' setting by reducing past 0%.

How to use

  1. Open the menu in a dark world.
  2. Go to MODS and adjust settings.

Installation via Deltamod/Deltahub

Full game — custom-difficulty-drmod-fullgame-{version number}.zip

Demo — custom-difficulty-drmod-demo-{version number}.zip

Installation without a mod-manager

Windows

Quick start

  1. Download and unzip the release.
  2. Double-click install-windows.cmd.

Installer does

  • Detects your DELTARUNE install (prompts if needed)
  • Downloads UndertaleModTool CLI if missing
  • Backs up originals to ModBackups/<timestamp>
  • Patches all chapters; safe to re-run
Command line 
.\install-windows.cmd
If Windows blocks it
  • SmartScreen: “More info → Run anyway” or right-click → Properties → Unblock
  • Permission errors under Program Files/Steam: run as Administrator

macOS

Quick start

  1. Download and unzip the release.
  2. Double-click install-macos.command.

Installer does

  • Detects your DELTARUNE install (prompts if needed)
  • Downloads UndertaleModTool CLI if missing
  • Backs up to ModBackups/<timestamp>
  • Patches all chapters; safe to re-run
Command line 
./install-macos.command
If macOS blocks it
  • Right-click → Open, or allow in System Settings → Privacy & Security

Linux w\ Proton

Quick start

  1. Download and unzip the release.
  2. Double-click install-linux-proton.sh.

Installer does

  • Detects your DELTARUNE install (prompts if needed)
  • Downloads UndertaleModTool CLI if missing
  • Backs up to ModBackups/<timestamp>
  • Patches all chapters; safe to re-run
Command line 
./install-linux-proton.sh

Advanced

Windows script flags (install-windows.ps1)
  • -Uninstall — restore from most recent backup
  • -NoBackup — skip creating backups
  • -GameDir <path> — set DELTARUNE folder path
  • -UtmtCli <path> — path to UndertaleModCli.exe

Example:

.\install-windows.ps1 -NoBackup -GameDir "D:\Games\DELTARUNE"
macOS script flags (install-macos.command)
  • --uninstall — restore from most recent backup
  • --no-backup — skip creating backups
  • --app <path> — path to DELTARUNE.app
  • --utmt <path> — path to UndertaleModCli

Example:

./install-macos.command --no-backup --app /Applications/DELTARUNE.app
Linux w\ Proton script flags (install-linux-proton.sh)
  • --uninstall — restore from most recent backup
  • --no-backup — skip creating backups
  • --game-dir <path> — set DELTARUNE folder path
  • --utmt <path> — path to UndertaleModCli

Example:

./install-linux-proton.sh --no-backup --game-dir /Games/DELTARUNE
Manual install (UndertaleModTool CLI)
  1. Download UndertaleModTool CLI for your platform
  2. Extract it next to the game files
  3. Apply scripts in this order: modmenu_ch1to4.csx then customdifficulty_ch1to4.csx

Windows

UndertaleModCli.exe load "chapter1_windows\data.win" --scripts "src\modmenu_ch1to4.csx" --verbose false --output "chapter1_windows\data.win"
UndertaleModCli.exe load "chapter2_windows\data.win" --scripts "src\modmenu_ch1to4.csx" --verbose false --output "chapter2_windows\data.win"
UndertaleModCli.exe load "chapter3_windows\data.win" --scripts "src\modmenu_ch1to4.csx" --verbose false --output "chapter3_windows\data.win"
UndertaleModCli.exe load "chapter4_windows\data.win" --scripts "src\modmenu_ch1to4.csx" --verbose false --output "chapter4_windows\data.win"

UndertaleModCli.exe load "chapter1_windows\data.win" --scripts "src\customdifficulty_ch1to4.csx" --verbose false --output "chapter1_windows\data.win"
UndertaleModCli.exe load "chapter2_windows\data.win" --scripts "src\customdifficulty_ch1to4.csx" --verbose false --output "chapter2_windows\data.win"
UndertaleModCli.exe load "chapter3_windows\data.win" --scripts "src\customdifficulty_ch1to4.csx" --verbose false --output "chapter3_windows\data.win"
UndertaleModCli.exe load "chapter4_windows\data.win" --scripts "src\customdifficulty_ch1to4.csx" --verbose false --output "chapter4_windows\data.win"

macOS

./UndertaleModCli load chapter1_mac/game.ios --scripts src/modmenu_ch1to4.csx --verbose false --output chapter1_mac/game.ios
./UndertaleModCli load chapter2_mac/game.ios --scripts src/modmenu_ch1to4.csx --verbose false --output chapter2_mac/game.ios
./UndertaleModCli load chapter3_mac/game.ios --scripts src/modmenu_ch1to4.csx --verbose false --output chapter3_mac/game.ios
./UndertaleModCli load chapter4_mac/game.ios --scripts src/modmenu_ch1to4.csx --verbose false --output chapter4_mac/game.ios

./UndertaleModCli load chapter1_mac/game.ios --scripts src/customdifficulty_ch1to4.csx --verbose false --output chapter1_mac/game.ios
./UndertaleModCli load chapter2_mac/game.ios --scripts src/customdifficulty_ch1to4.csx --verbose false --output chapter2_mac/game.ios
./UndertaleModCli load chapter3_mac/game.ios --scripts src/customdifficulty_ch1to4.csx --verbose false --output chapter3_mac/game.ios
./UndertaleModCli load chapter4_mac/game.ios --scripts src/customdifficulty_ch1to4.csx --verbose false --output chapter4_mac/game.ios

Linux w\ Proton

./UndertaleModCli load chapter1_windows/data.win --scripts src/modmenu_ch1to4.csx --verbose false --output chapter1_windows/data.win
./UndertaleModCli load chapter2_windows/data.win --scripts src/modmenu_ch1to4.csx --verbose false --output chapter2_windows/data.win
./UndertaleModCli load chapter3_windows/data.win --scripts src/modmenu_ch1to4.csx --verbose false --output chapter3_windows/data.win
./UndertaleModCli load chapter4_windows/data.win --scripts src/modmenu_ch1to4.csx --verbose false --output chapter4_windows/data.win

./UndertaleModCli load chapter1_windows/data.win --scripts src/customdifficulty_ch1to4.csx --verbose false --output chapter1_windows/data.win
./UndertaleModCli load chapter2_windows/data.win --scripts src/customdifficulty_ch1to4.csx --verbose false --output chapter2_windows/data.win
./UndertaleModCli load chapter3_windows/data.win --scripts src/customdifficulty_ch1to4.csx --verbose false --output chapter3_windows/data.win
./UndertaleModCli load chapter4_windows/data.win --scripts src/customdifficulty_ch1to4.csx --verbose false --output chapter4_windows/data.win

Notes

  • Back up your files first
  • Apply modmenu before customdifficulty
  • On macOS, chapter folders live in DELTARUNE.app/Contents/Resources/

Compatibility

Saves: Compatible with vanilla saves. The mod reads and writes to a new .ini file; no change to vanilla save data.

Other mods: Not guaranteed. This mod makes specific line edits to the dark world menu, various damage scripts, enemy attack code, and battle controller code; so those areas will be the source of any potential conflicts. Mods that avoid those areas are more likely to work.

About

Mod that adds difficulty options to Deltarune. Make the game easy, hard, or nightmare! ( or no-hit! )

Topics

game-mod deltarune mod-menu deltarune-mod custom-difficulty-mod difficulty-mod no-hit-deltarune easy-mode-deltarune hard-mode-deltarune

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Releases 13

Custom Difficulty Mod (v1.6.1) for DELTARUNE (v1.04) Latest
Jan 10, 2026
+ 12 releases

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