Touch controls are inherently less precise than a keyboard or controller. Test your bullet patterns frequently on your phone to ensure they are actually fair and beatable for mobile players.

While technically a fan-game, Last Breath includes an advanced battle simulator. It allows you to fight against custom waves of enemies. While you cannot code new enemies directly inside the app without file editing, it is the gold standard for playing high-quality custom battles on Android.

Enter the world of —a suite of mobile applications that put the power of the Underground directly into your pocket. Whether you want to fight Sans on a bus or design a unique OC (Original Character) boss fight to share with friends, this guide covers everything you need to know.

: This app focuses on storytelling and scenes. It includes a Movie Maker for stop-motion animations and a Scene Creator

The most famous example, focusing heavily on the Sans boss fight.

Download a mobile text editor that supports Lua syntax highlighting.

These are projects designed specifically to emulate the Undertale fight system (bullet hell + dialogue menu). Undertale Engine / CYF (Create Your Frisk) Ports: What it is:

As you begin creating your own battles, keep in mind the following tips and tricks to ensure your creations are engaging and fun:

: Custom text boxes, fonts (like Comic Sans and Papyrus), and the signature typing sound effects.

Building a fight requires balancing fairness with difficulty. Follow this structure to get started: Step 1: Prepare Your Visuals

Creating a battle involves several steps, usually managed within the app’s "Editor" mode. 1. Character & Scene Setup

Touch-screen optimized controls and pre-built templates.