This RPG thing I thought up

mike@puddingtime.org (mike) — Thu, 30 Apr 2026 19:50:48 +0000

I like Rogue. I loved old dungeon crawlers in the 8-bit era because they couldn’t do that much. So I was sitting around thinking about something fun to do and decided to make a very simple web-based RPG.

After a little research, I picked an RPG engine (Cairn) because it has an open license and there’s plenty of creature and loot content out there.

The game is pretty simple, but I picked two things to customize/make customizable:

First, the game content (creatures, treasures, settings) are all defined in YAML files:

- id: root_goblin
  name: Root Goblin
  str: 8
  dex: 14
  wil: 8
  hp: 4
  armor: 0
  attack: { name: "spear", die: "d6" }
  special: null
  tier: weak
  weaknesses: [poison]

- id: hooded_thief
  name: Hooded Thief
  str: 10
  dex: 12
  wil: 6
  hp: 4
  armor: 0
  attack: { name: "dagger", die: "d6" }
  special: null
  tier: weak
  weaknesses: [greed]

Once I’ve got it working with the initial data, I want to make the data files interchangeable and write a Claude Skill that lets the player answer some simple questions about atmosphere and setting that generates a custom YAML file.

Note the weaknesses field: That helps drive the next feature:

The first thing I noted trying to playthroughs using stock Cairn rules is that it is a super unforgiving system. The game requires you to get through 13 rooms, and I couldn’t make it past four without fleeing a lot. I considered nerfing things, or buffing the characters, but I was also just finding the game itself pretty boring.

So I’ve added an AI GM (a Haiku API call). When you encounter a creature, you can do the usual attack or flee, but you can also improv using anything in your inventory:

… and Haiku ajudicates:

For v1, I’m just kicking the tires on the virtual GM. Eventually, the same way I want settings, creatures, and loot to be user-definable, I want to be able to define the GM’s temperament: Everything from the classic by-the-book realism killjoy to what I’m calling “failed improv class instructor.”

You may have also noted with that Hooded Thief creature up there that there’s a weaknesses: [greed] field: The GM uses that to help it judge the effectiveness of your gambit: If you’re holding a coin purse and come across the hooded thief, it’ll get distracted if you just drop your money and run away.

I still want the game system to be a little tough, and still want to make getting to that 13th room hard, but it might as well be more fun along the way.

hi, it's mike

This RPG thing I thought up