After taking a break from js13kGames last year, we wanted to try something different and new this year. We're proud of our previous games, including Afterlife (2022), ESCAPE (2021), and Backcountry (2019), but we were never able to compete for the top ranks. In a sense, this realization was liberating. By accepting that we were not aiming for the top 10 nor even the top 50, we freed ourselves to do something more risky: a card game.

We have always been fans of card games, ever since we played Dominion in real life and on the now-defunct Isotropic implementation more than 10 years ago. We would often daydream and discuss making our own card game. However, virtually all games we made together were not card games. 2024 is the year when that changed.

Staś and Michał prototyping card games on paper.

Our story starts earlier this year, in March. We got into Marvel Snap and we felt that we would love to play a game like Snap, but single-player, with a heavy focus on deck building as part of the game's progression. We really liked Snap's three locations system which made us think of Gwent, except that it's spatial rather than temporal.

We also looked into one of Snap's inspirations: Smash Up. It's not really a deckbuilder in the common sense of the word, but you do build you deck in it by combining two preconstructed half-decks, each with its own mechanics. The game takes place across multiple locations which activate special abilities once a break-point is reached, i.e. once the total power of cards in the location reaches a certain threshold.

We started gathering notes and ideas, and we prototyped them using pieces of paper and blank playing cards. We weren't sure what kind of game we wanted to make at this point. Instead, we mixed and matched mechanics from other games that we enjoyed playing, spicing them up sometimes with an original twist. Our goal was to get started making a game and to see how it evolved over time.

A screenshot of our unreleased prototype code-named Lunapark.

We quickly moved on from paper prototypes. There was just too much stuff to keep track of given the mechanics we had in mind. We specifically wanted to replicate Dominion's crazy combos, which would produce screens and screens of logs on Isotropic. We need an implementation that we could play on a computer. Michał put together a prototype over Easter and we started exploring different concepts.

The card battles happened in three locations of which you needed to win two, similar to Snap. We dropped Snap's simultaneous turns—it makes sense in multiplayer PvP when mindgames are the core of the game. However for us, we knew we were building a single-player tactical puzzle, so we made the AI always go first, giving the human player a slight advantage.

We built a map similar to that in Slay the Spire. Inspired by Balatro, we experimented with giving the player the control over card order on the table, with some cards multiplying the power of cards before them rather than adding power themselves. We even added encounters and artifacts.

One thing that we struggled a lot with was creating a sense of peril between the card battles. We didn't want to introduce the concept of health into the game, but we knew that we needed some resource the would be scarce and which the player could conciously and strategically trade for some other benefit during their playthrough.

The earliest screenshot of Millennials, taken on August 15, two days after the start of the jam.

The jam's theme was announced on August 13th: Triskaidekaphobia, or the fear of the number 13. We instantly realized that it described perfectly the core gameplay twist that we based our unreleased prototype on: the deck could only ever have 12 cards! It's a rather unique departure from the deck-building genre.

The plan was as follows: we'll build a new game completely from scratch, based on the experience we got from building Lunapark. It's going to be smaller in scope: 60-80 cards, a few opponents, and no map between the battles. We'll come up with a different setting and create new pixel art for it.

We'll use the competition as a motivation to continue iterating the game. We'll playtest with the js13k community, and we'll get feedback from other participants during voting. The jam is our opportunity to show an early demo of our card game to an audience of 100-200 people whom we don't know and who are not going to say nice things just because they are our friends :)

And while we build this new game, perhaps new ideas will come to us, which will improve the game we want to build. (Spoiler: they did!)