Backpack Monsters – js13k 2019

Js13kGames is a JavaScript coding competition for HTML5 Game Developers. The fun part of the compo is the file size limit set to 13 kilobytes. The competition started on 13th August and ended on 13th September 2019. The theme for 2019 was back.

I managed to participate in the competition for the third time in a row, this year I created a monster-catching game. You can play online here or here. Source code is here.

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The game itself is pretty simple, you walk around the map using the cardinal directions, and when you land on a spot you may find a monster and catch it. Both moving and attempting to catch a monster will consume your action points, which replenish automatically every 20 seconds to a maximum of 40. It works in both mobile and desktop browsers.

The organizers were encouraging the participants to integrate with coil.com and XRP tip bot to monetize their entries, I implemented a simple bonus for coil subscribers (they get a 25% bonus on the speed for action points to recover). So far I have received 1.08 XBR (That’s Ripple cryptocurrency,  converting to about 0.3 USD today)

The Story

What was my motivation this year? I was really hesitant to participate since I’ve been busy with other projects and just participating for the sake of it was not enough of a reason. Certainly, after last year’s results, I didn’t care much about “winning” the contest.

So, in the end my motivation ended up being merely to create an interesting procedural generator, to hone my procgen skills. I had just tried to participate in “Advanced Topics in Procedural Content Generation” online summer school provided by the IT University of Copenhagen and New York University, where I was able to watch some talks and gain some insights, but failed to participate in the course project.

The weeks before the challenge started I had an idea for a procedurally generated sports event (that thing has been in my head for some time now), but it was not very compatible with the theme they announced (“Back”). For most of the month, I couldn’t come up with something fun and interesting, that only managed to happen in the last week. So I started late and only managed to invest about 5 days on it, but the last days were super intense.

Being a pokemon fan (and a somewhat proud genwunner), I always wanted to create a monster-catching game (well, I kind of already did). Some years ago I was even working on a Pokemon Go-like game, but it never lifted off due to missing some original designs for them monsters.

So, I thought I could take another stab at a similar project, using procgen to fill the gap. I started by analyzing some pokemon anatomies and coming up with their structure and even used tracery.io to have an idea of how this “taxonomy” was looking (I had wanted to use it for something, for years :P). Sadly I didn’t include these descriptions in my final entry. (then again, I dunno how big the JS lib for tracery is)

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Then, I started setting up the project, reusing the structure from my previous entries. In keeping my idea of NOT using pixel art on new projects, I thought of reusing the vector rendering routines I had used in these previous entries, however, the shapes I was planning to use were going to be more complex (I was initially thinking on trying to replicate the look of the original pokemon, like this one), so instead of just coding them by hand I used some online SVG editors and then manually translated the SVG instructions into my rendering routine.

However, as I needed to produce more complex shapes (mainly supporting bezier curves), I found out it would be more straightforward to generate SVG objects rather than extending the “vector script” I had in place, which by coincidence was pretty similar already to the SVG path definitions. This became more important as I looked for ways to get an artist to help me with content for the game since I would have had to translate SVG into my own script language, either manually or automatically.

So I ditched rendering paths and shapes into the canvas and instead started experimenting with generating SVG components from code and overlaying them using CSS.

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As the deadline drew closer, it became obvious that I would not be able to replicate the appearance of the reference I had for the monsters in a convincing way. I looked around a lot and finally found something in Etsy that I could use as a reference for my generator. (sadly, the store and the item itself seem to be gone now. Good timing for me tho!)

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These designs had several advantages:

  • They were portrayed as a symmetrical front view
  • They were more “symbolic”, without relying on individual poses for personality.
  • They were “inspired” by the original Pokemon designs, so not a direct knock-off.
  • They were already provided in SVG format.

I bought it, thinking I could at least cut and paste the different body parts and use them as individual SVGs, but my skills with both Illustrator and Inkscape proved not to be enough for it. Luckily, js13k colleague Rybar came to the rescue and helped me with the task, probably having to redo a lot of SVG work following the references.

Now with the individual SVG assets provided by Ryan, I could finally advance in the actual generator, having, at last, some progress to show.

The generator works by picking a random “anatomy” which determines the body parts slots the monster will have, and their location. then it proceeds to select a random type of body part for each slot and positions them together using some anchor points.

It also picks a random “pastel” color for the monster, I did some research and found out an easy way to generate them was using the HSL model, and having both Saturation and Lighting at 70%, and picking a random Hue. Luckily, CSS supports defining colors with the HSLA notation so this was pretty easy to include.

I also build a simple, syllable-swapping based name generator for the monsters. It generates names using two to three syllables, picking from a random list of consonants, vowels and a possible third consonant, for each syllable.

It’s also worth noting that this generator is seeded, which means the “races” of monsters that are generated are always the same, and all players will get the same set! For this, I reused the simple (on implementation!) but effective Park-Miller LCG

Now that I was finally generating some content, I focused on creating an actual game around the generator. I knew from the onset the game would not be deep, but there had to be a game!

I created a world represented by a 10×10 grid of locations and added a simple name generator for them (reusing the monster name generator but also adding some flavor with location types and colors). Also added the energy system to move around and catch the monsters, to serve as a barrier for content consumption.

In the world model, I placed lists of monsters for each location, considering their “rarity” so that very rare monsters can only be found in a single location, and so on. The idea being that players could share their findings, creating something of a social aspect to the game (Hey, what monster are you missing? I found Lesense in the Temple of Serkekol!).

I added a simple model to keep track of the monsters you had captured, and a view where you could see them.

I had managed to have a playable game one day before the deadline, so I could focus on enhancing the UX and testing. Needless to say, this ended up consuming a lot of energies but the end result was very good.

I managed to include a music track (thanks again to Rybar for creating it!) and even modified it in the tracker to make it longer (first time I make something useful using a tracker). We used SoundBox again (here‘s the final version of the track)

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I also made the game public and asked around for suggestions to improve it, one of them was adding more variations to make the monsters feel more unique. I fired Inkscape and drew a lot of horns, antenna, mouths and some tails, and also defined an additional anatomy with no “body” (just a head with things attached to it). The structure that was in place made it very easy to add new content.

Also, in order to add some “depth” into their appearance, I was suggested to do some shading into the bodies, which I managed to do with the help of Prinfexita, a fellow indie dev from Colombia. She drew the shadow shapes and I added support for them into the generator (including producing a darker version of the body color)

I also did a LOT of tweaks on the user interface, to make navigation easier for the players and provide a cleaner experience, especially in mobile.

What went right

  • I was able to create a finished, stable and polished experience
  • I learned a bit more about SVG
  • I created something technically different than last year entries.
  • The monsters look cute.
  • I was able to collaborate again with Ryan Malm, for the first time with graphics and for the second time with music.

Inadvertently, I think I managed to do just what I set to do from last year’s postmortem:

  • An easy game, rewarding players without requiring lots of skill.
  • Gorgeous visuals. (Maybe??? :))

What went wrong

Nothing really went wrong, however, there are some core things I wish I had managed to include to make my entry more fun:

  • A scrolling map view of the world, since right now it relies a lot on the player imagination
  • Deeper gameplay mechanics for catching the monsters, maybe collecting some items in the world that would help you lure them.
  • Allow trading monsters with other players.
  • More body parts, especially Wings and tails
  • Scaling variations for the monster’s appearances.

But all in all, I’m very happy with what I was able to create in the short time frame.

However, I got pretty sick and weak for two days after the deadline, I believe I pushed too hard. Would be better to avoid crunch by starting earlier.

The Future

I never intended the game to be more than just a collecting game, so things like a plotline or a combat system were willingly ignored.

Some other things that would have been nice to have, as possible points of expansion:

  • A more in-deep generation of the monster anatomies beyond randomly selecting and swapping parts.
  • Generate monster descriptions and stories.

 

 

 

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