This is a simple 5e encounter simulator. It is showcased in the following Youtube video: https://www.youtube.com/watch?v=A8FNVkFuhXI

The simulator calculates the "average" game using probabilities, which means it runs slightly differently than an actual game of 5e:

• A creature gets to act if it started the round with more than 0 hp
• Heals, buffs & debuffs are applied before attacks
• Debuffs are multiplied by the chance to actually receive that debuff
• Damage from attacks is multiplied by the chance that this attack hit

This does result in slightly different outcomes than if the simulator used statistics (running the simulation a large number of times, using random dice rolls, and measuring the result).
For example, if a creature has 10 hit points and becomes the target of an attack dealing 10 damage that has 50% chance to hit, it will be shown to have taken 5 damage, when in the actual game, it would have taken either 0, or 10, never 5.

It might change in the future, but for now, the reason this approach was chosen is that:

1. A probabilities-based approach makes the visualization easier.
2. A statistics-based approach is more computationally intensive.

• Install nodejs: https://nodejs.org/en
• Download node packages: npm i
• Run in dev mode: npm run dev
• Open http://localhost:3000 with your browser to see the result.

• public: images to be displayed on the website
• src
  • components: UI elements
    • creatureForm: the dialog which is shown when clicking adding/updating a creature
    • simulation: the components for showing the simulation's results on the home page
    • utils: general form elements
  • data: list of monsters & PC templates to populate the UI
  • model: type definitions, enums, and the core of the simulation
  • pages: HTTP URL endpoints
• styles: global CSS

To contribute, fork this repository and make pull requests.

This project's main goals are to:

• Streamline the process of inputting an encounter as much as possible without sacrificing the output's accuracy
• Give the user a clear understanding of what's happening, so they can decide whether or not the encounter is right for their table

Contributions that are likely to get accepted:

• Templates for multi-classed characters
• Streamlining of the UI (e.g. scanning a PC/monster on dndbeyond from just its URL, and making an educated guess about its gameplan)
• Improving the result's clarity (e.g. "luck sliders" to see multiple scenarios and quickly see how swingy an encounter is)
• Tightening the simulation algorithm to make it more accurate (e.g. making sure the order of the creatures does not matter)

Contribution checklist:

• Make sure the project compiles with npm run build
• Make sure the contents src/data are updated to reflect your changes
• Make sure your changes are backwards-compatible with the save files a user might already have in their local storage

Common reasons why a pull request might be denied:

• It makes the UI too tedious to use.
• It makes the result too confusing to read.
• It adds too much data to the monsters, and risks breaking the terms of the WotC Fan Content Policy

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

The license only covers commits on the main branch made after June 2nd, 2023, and only the contents of the src and styles directories, with the exception of:

• The src/data directory
• The src/components/utils/logo.tsx file
• The src/components/utils/logo.module.scss file.

BattleSim is unofficial Fan Content permitted under the Fan Content Policy. Not approved/endorsed by Wizards. Portions of the materials used are property of Wizards of the Coast. ©Wizards of the Coast LLC.