Hi Chris,
This is probably not the same game? Very few people play my games at cons, I would wager, if any. I think the only game I've made that actually has a small "fanbase" right now is This Town Is Full Of Monsters, and maybe Passage as a distant second. Those are much smaller, GMless storytelling games (with Passage being a solo game by default, though it can be adapted for groups), and I suppose they could theoretically generate pretty dark stories, but TTIFOM is the only one that encourages the use of cards, and very optionally at that.
I'd guess, based on your description, that you might have simply played a different game named Spiral, by a different designer? Sometimes that happens, as it can be very difficult to make sure that two indie rpgs don't have the same name when neither author knows about the existence of the other at time of publication?
Or maybe "spiral" was simply the thematic and mechanical core of that system, since it seemed to encourage continual escalation (that sounds like a really cool idea)?
My Spiral, I am afraid, is not nearly as mechanically innovative as that. It does feature a spiraling / cascading fatigue system, which is probably where I got the idea for the name (it was so long ago that I honestly can't remember), but, as you can probably tell from the page count, it's more of a "old school" rulebook for a multipurpose, generalist ttrpg system. Kind of an OSR-ish thing, I suppose. I think I actually started working on it in college, which is, horrifyingly, two decades ago now, and it was basically my attempt to smoosh together the few things I liked about traditional DnD and the BRP system. It's probably the stuffiest and most "formal" system I've written, but I suppose I'm still pretty proud of it. Most of the ones written since have been a lot looser, and smaller.
The DrivethruRPG suggestion is, in fact, a very good one. I do already host all of my (tabletop) games on there under the "brand" Cloudmonster Press. It does generate a lot more organic sales that itch.io (which really generates almost no organic sales to speak of - most come from me occasionally advertising on social media), but they do take a much bigger chunk of the profits, so it kind of balances out. Still, I would recommend any indie designer who wants to make a bit of extra coffee money off their games to always do both.
Anyway, if you find out which game it is that you played, I'd be curious to know as well. It sounds pretty cool.