29 September 2025 ☼ tabletop ☼ design ☼ Undersong ☼ World of Sanctuary
Undersong, my fantasy role-playing game inspired by Hollow Knight and Hollow Knight: Silksong, is out now on itch.io and is absolutely free. But how did I end up writing a fairly traditional tabletop RPG based on a new and popular video game franchise? Why, that sounds like fertile territory for a designer diary, my friend.
About six weeks ago, I got tapped to run a campaign for a pretty mixed group of folks, going from absolutely zero tabletop experience to at least one person who might even have more hours wasted pretending to be an elf than myself. The request was specifically for something D&D-like, so I tucked in and started looking around for something kinda-OSR, kinda-PbtA that I would enjoy running and that wouldn’t feel so off the mark as to be confusing for a newbie.
I… I looked at a lot of games, yo. I initially wanted to go with my absolute favorite of the options in this category, Freebooters on the Frontier 2E, but I figured it would be a little more involved than the group would have been comfortable with. So, I went over all the traditional Hacks (Black, Blue, White), the family of Knave and Maze Rats derivatives, and a few games I hadn’t previously heard of (Realms of Peril, Grimwild, Wildsea) and nothing really jumped out as having everything I wanted/needed in a system to run. Add to this the fact that the group was excited about the campaign pitch I gave them as an excuse to try using the Downcrawl supplement and I ended up doing the stupid thing every designer ends up doing at least once: I wrote a hack that stitched together all the bits I thought I needed.
But, like, that by itself is not really an interesting diary, is it?
The initial result was a game I called “Undervale”, which on a lark, I’m actually going to make available right here. We’ve played a couple sessions of it and had a good time! Immediately, though, a couple things happened.
First off, I wanted to start changing things based on friction points this particular group had with the game. The major examples:
Undervale’s encumbrance system allows you to carry a reasonable number of “regular” items, and a drastically limited number of “heavy” items. The intent here was to mimic Knave’s item slot system, but in practice, everyone kind of just found the limited number of “heavy” slots frustrating rather than an interesting choice. I’ve gone back and forth on it over the years, but frankly I think I’m coming down hard now on the side of “encumbrance and inventory systems are only fun if they are the primary focus of the game”. Like, the best basic D&D I’ve played has always been low-level, scrappy and resource-focused. Is it worth losing some HP and possibly my character to get a little more treasure here? How much of my gold should I spend on torches and supplies and how much should I be saving for healing/resurrection? Basic D&D combat is really just an exercise in seeing how many resources you end up losing because you either decided to take a risk or failed somewhere in your planning. In a game where combat and exploration is a bit more of a focus, maybe you don’t need to decide between +1 armor or an extra pack of torches (heavy), so I nuked any sort of encumbrance system.1
Because inventory was now wide-open, I needed to change course a bit on addressing some of the fiddlier parts of the exploration/mapping mechanics that were mostly brought over wholesale from Downcrawl. The group wasn’t clear on or particularly engaged with the “use resources to create new areas to explore” mechanics (sob)2, but intuitively understood how valuable bearings, the resource the game used for traveling/mapping, were. I decided to lean right into that and made them functionally act as “travel supplies”. Pretty abstract? Sure, but so are video games.
I borrowed the “pick your own class name and get a bonus when you act with it” mechanic from Fabula Ultima, but it proved to be a good example of how additional constraint can sometimes breed creativity. Characters sprouted more from attribute/starting item rolls (thanks Mothership) and pre-existing ideas than anything else, which meant summarizing the character in a couple words at the end of the process felt jarring, especially since it had an important effect on gameplay. Undersong has classes, called “Crests”. You want to rename your Crest? Go right ahead. Sometimes (oftentimes) simpler is better.
Realms of Peril has a neat “raise your attributes after failing a check” rule that I adapted to the more common “if you fail a check with one of your attributes when you level up, raise that attribute” mechanic. Of course, that mechanic is only more common to me: it proved to be hard to explain to a mixed group. I swapped over to a “raise an attribute after failing X checks with it” rule instead, which I’m much happier with.
There were a few more things, certainly, but let’s get to the second big thing that happened: Hollow Knight: Silksong shipped.
We were already playing a game at least partially about traipsing through Hollow Knight-esque caverns and fungal forests, and so I figured if I was going to gut a handful of the mechanics anyway, why not do a bit of a reskin at the same time into something a few of us were obsessed with?
Once that work was done, the game actually had a lot more original material than I was initially expecting, and so it was just a little more work to trim things to the “24 pages max” rule I arbitrarily set for myself years ago, as well as add some oracle charts that a person might need to actually run the game itself without supplementary resources. Jade made some really nice key and cover art for the game, and now it’s up for everyone to play.
Honestly, I didn’t ever think I’d ship something as close to a traditional fantasy tabletop game as this (it has the basic 6 attributes! it uses polyhedral dice!), but it was fun to go from start to finish on something in only six weeks. Undersong will remain free for the foreseeable, but my plan is to eventually finish up a third video game-inspired 24-page ruleset and then bundle it and some bonus content together with this and World of Sanctuary. We’ll see if that ever comes to fruition. In the meantime, I’m digging back into my other tabletop project, so hopefully I’ll have more to talk about that very soon!
As an aside, my Diablo-inspired game World of Sanctuary uses a more explicit slot-based inventory system, but it and Diablo are both games about loot. The original version of the game was played in person and used index cards(!) and bespoke dice(!!!) to track loot drops and player inventory, and I think it mostly worked and mostly translated OK to the mostly-for-digital-play version that exists now.↩︎
I think a lot of this is due to us stumbling into a fun concept for an adventuring hub early: a trio of underground villages built around big, fat, sleeping dragons. The dragons (and the villages) are named Dozin, Snorn and Dremp. No, I make no apologies.↩︎