Postmortem: ArcherFire Duet of Aces – js13k 2018

ArcherFire: Duet of Aces is a game I made for the js13k 2018 contest, you can check it out here! (and the source code is here)

I decided to write one final piece of text about my second participation on the contest. I already described my journey in detail here and here, and also did a dissection of the source code, but I wanted to record some lessons learned which may come in handy for other people or myself in the future.


The story

Whenever I participate in a game jam or contest, I ask myself what is my motivation:

  • Learn a new language or tool
  • Create something cool
  • Win the contest prize

This was the second time I participated in the contest; results from last year had been a bit disappointing (regarding the ranking given by the jurors), and I knew my development time this year was going to be very limited. Still, I aimed to rank high into the lists.

The theme for this year was OFFLINE, as mentioned in my first blog post, I started off with a vague idea of a space… thing… where you could collaborate with other players offline to advance through the game.


On the first day of dev, I created some foundations work looking forward to having some kind of space sandbox thing with arcade elements (Similar to this entry, which ended up being one of the contest winners). However, given the constraints I had, I decided to follow my own advice from last year’s postmortem and create:

  • An arcade game bringing full action from the first second of gameplay
  • Complete music track

And that’s precisely what I ended up doing! Interestingly, and maybe because of what I set to do and my experience from last year, I didn’t have any issues with the 13KB limit so I didn’t have to cut around any corners. I incorporated the OFFLINE theme by allowing 2 players hot-seat offline play.

However, the results were even less encouraging this year. Despite receiving good feedback from the jurors, the game didn’t even end up in the top 100. (Last year it ended up #40 overall and ranked well in the Community and Social lists). Since this was the first year where some constraints were put on the prizes model (only top 100 entries would get prizes) that meant that effectively I lost the contest. There was a total of 270 entries, and mine ended up ranked #105.

Screen Shot 2018-10-18 at 6.35.57 PM

Unlike last year, this time I don’t really have some big factors I think led to this result. I contented myself in thinking that the jurying process is not perfect, and there may have been very good entries this year. Still, here’s what I think worked and didn’t work.

What went right

  • Seeded Procedural Generation: Managed to create an infinite, increasingly harder, top-down shooter level which was the same every time you played (So, in theory, the more you play the game the more likely you are to memorize the hazards and get farther)
  • Pseudo 3D Effect: Everyone loved how cool the ships looked when soaring around.
  • Straightforward action-packed: The game is pretty responsive and quick, with lots of action on screen. No need to explain anyone how to play because it’s obvious!
  • 2 players hot-seat mode: I couldn’t test this much because I have no friends, but I saw some people have fun and yell at each other afterward.
  • A solid, finished entry: No bugs, no feeling of being an “incomplete game”, it is what it is and it doesn’t break.
  • Music: One of the game highlights, and I didn’t do it myself 😀 it was all thanks to Ryan Malm. I just gave him a reference and some ideas, and he came up with the track. Thanks again!

What went wrong

  • Floaty Controls: Since my foundational work on a simple physics engine had support for acceleration, I stuck to the end with the idea of the ships being “hard to control” as a “challenging aspect” for the player. I knew it was frustrating, but I waged on the players trying harder to learn how to control it. In the end, it ended up being too hard and too different to the standard. A model where the ships had less inertia would have been much more playable and enjoyable. Maybe I need to start making easier games!
  • Balancing: Some people reported the game was a bit too hard. In part, this may be closely related to the controls, but also could have lessened the hit points of the enemies or made the difficulty curve less step.
  • Lack of theme: Yet another space shooter, no plot, maybe went too much into the arcade direction? So that aspect was pretty uninteresting. There were also too few types of enemies, mainly because of the time constraints I had.
  • Graphics too simple: I am not an artist, and the game had high-resolution vector art. Unlike last year where I could go around that by using shadows in the darkness, this year I went for colors and maybe it didn’t look too nice. One thing that could have worked would have been using WebGL filters to post-process the bare graphics, which has worked great for other games in the past.

The Future

This is not the end of the story for Duet of Aces… I plan to make it evolve into a more complete game, keeping the core design but adding better art, sound effects, more music, a complete plot and more importantly, adapting it to social media mobile platforms. More info soon!

Also, some things I want to do next year:

  • An easy game, rewarding players without requiring lots of skill.
  • Gorgeous visuals.

Ananias RoguelikeCel 18 Tournament!

The Roguelike Celebration 2018 is coming! We are celebrating it with a new Ananias Roguelike tournament with Cool Prizes! are you bad enough to win the tournament?


1st place 2nd place 3rd place 4th place 5th place
Money 50$ 20$ 10$
Ananias Box with instruction booklet X
Original Art Card X X X
Paladin Red T-Shirt X X X X
Ananias Stickers Set (8) X X X X X


How to participate

  • Share your Gravestone page, including a screenshot of your journey, via twitter using the #ananias18 and #roguelike hashtags. (See here for a Gravestone page)
  • You are also encouraged to share it on reddit but it’s not required
  • You can submit your character any time before October 7, 4PM PST
  • Participate playing in any valid official 2.4.4 version of the game, including Android, iOS, Steam and Web. No Fellowship Edition required.
  • You can also participate playing in person in the Roguelike Arcade at the Celebration (but it’s not required)
  • Winners will be picked based on the standard scoring criteria (depth level, then kills)
  • You can use any class / pet combo


  • Money Prizes to be awarded via Paypal
  • Ananias Box and Manual – No diskette
  • T-Shirts available in limited sizes – To be awarded as available.
  • Sticker set will contain assorted characters as available.
  • Physical prizes will be delivered in person at the Roguelike Celebration on Sunday October 7. If you are not attending then they will be sent to you for an additional Shipping cost to be paid via paypal.


  • How can I get the gravestone page for my character?

Just create an account in the game, and then when your character dies or ascends use the “Gravestone” button


OpenArthurianX6 – Enemies doing ranged attacks

Making the enemies being able to attack the player with ranged weapons required two things: first was allowing defining initial inventory for mobs (so that they could have ammunition for the weapons).

This was already possible for NPCs, but not for MobTypes. I considered merging this data together but rather decided against it so that you could have NPCs share MobTypes without having to duplicate data. So now you can define initial inventory for both (and it will be added together).

After modifying the “base” mobs tileset to handle two types of soldiers (swordSoldier and xbowSoldier) with different weapons and inventory, I ran into problems with the process of embedding the tileset on the tiled map. It just doesn’t seem possible to update the embedded tileset with modifications (Once embedded it’s copied into the map, and I couldn’t find a way to replace it without deleting the tiles that were already using it).

However, on a second thought, I think it makes sense for the mob types and NPCs to be used in a given map to be embedded as tiles on its tileset. This means I’m ditching the idea of a “master” external tileset for the mobs, instead, each map will have tiles with custom properties for it.

Once that was in, I implemented some basic AI for the enemies, if they have a ranged weapon and there’s a clean LOS, they will fire instead of bump-attacking. This worked well, however, I hit a problem with the hybrid realtime-turn based model since the combat mode was not being kicked until the projectile animation was over, it was possible to affect the flow just by moving around evading the projectile while on exploration mode.


Plans for M1 are looking good, this is the list of pending tasks:

  • Implement “triggers” in combat based on a number of turns passing.
  • Transport to another map via trigger outcome
  • Fix bug: NPC interaction depending on having pressed a key
  • Fix bug: Crash when all party members killed
  • Add indicator for party member’s HP (New)
  • Fix conflict between party members and friendly NPCs in combat

All this should be done by the end of the week.

I’m also in the process of setting up a website for the project. This includes it having a logo, so if you think you can contribute with a cool looking logo, please let me know 🙂

OpenArthurianX6 – SkyBox tweaks

Back to development!

Added a mask for the celestial bodies on the skybox, tried first with a sprite mask but then realized a simple rectangular mask would work just as well.

Next up was sky color, dug up a very old sky color calculator thing done originally for Pixal in 2009

Screen Shot 2018-09-22 at 1.54.11 PM

Also found these notes which seems I used to code it :

atmosphereBase: Universe is black always, right?

lightStrengthForTheHour (Sun)

       0.0 ----------> 0.3 0.7 0.9 ------> 1.0 ------------------> 1.0 ------> 0.9 0.7 0.3 --------->
 HOUR  0   1   2   3   4   5   6   7   8   9   10  11  12  13  14  15  16  17  18  19  20  21  22  23

baseLight: Stars emit white light.

It seems like the core of the tool is an interpolation function for these values, coupled with some research on how light works in the atmosphere (over-simplified of course). I went ahead and used the original old source code (probably one of my first works in JS) and transformed it into a decent module. It’s now integrated into the engine, in theory, this would allow to change some attributes of the atmosphere and have the color of the sky respond (small details, but it’s fun).

Screen Shot 2018-09-22 at 10.58.53 PM

Also allowed defining items for the NPCs, which allows Shamino to fire arrows.

Been considering how the UI should work (full-screen map vs. a layout similar to U6). For now, I think I’m going to continue on the route to create an exult/nuvie-like layout with floating windows. This also means much smaller reliance on the events log/messages window for things like combat, the damage will instead be shown on screen, for starters.

Another thing I’m considering is merging MobTypes and NPCDefinitions, I see a lot of overlap there, and it’s causing the code to be more complex than it should, what I’m thinking is a single list, so you’ll be able to define what a generic skeleton is, and in the future make spawners for them, but in the same set of definitions you would have for example Shamino, including his full dialog and initial equipment the current way things are laid out you reference a mob type from the npc definitions, but I’m finding out that most of the times you will not reuse an existing mob type….

Unless maybe if we need to have a lot of NPCs, reusing the same basic definition for a “townsman” or “children”… gotta think about this more before making the moves in the code

ArcherFire: Duet of Aces, js13k 2018 source code dissection

JS13k 2018 has gone by! this is the third of a series of posts detailing my journey, as well as the structure of the game I built. You can play it online here!


Links to the full series: part1, part2, postmortem

The full source code of the game (github repo), uncompressed and unminified, is 43136 bytes for the single javascript file, plus 349 bytes for the html file. This includes a lot of comments and code that could be written in a more optimal way, which reflects that my biggest restriction this year was not the size, but the time I could invest in the project.

Screen Shot 2018-09-21 at 10.02.50 AM

Following is a summary of the 43136 bytes, which of course could be laid out in a much better, modular way, but were thrown together in a huge file for the sake of reducing overload from webpack for having multiple modules.

So, why do I think this may be relevant? Well, I believe this may be a bare minimum setup to have an arcade game up and running; understanding how these components work together to create the game experience might be helpful to create a more organized structure, without falling on the mistake of over-engineering (start small and simple!).

Also, having them all in a monolithic block creates an implicit graph of dependencies, where the more general purpose components are (generally) defined first, then other code uses them. Here’s a first stab at translating that to a component / class / object diagram.

Screen Shot 2018-09-21 at 10.50.36 AM

With each segment of the source code, I’m including a short description which may give you an idea of the types of components in play for the game, here we go!

  • Soundbox player (11879 bytes): Pasted from here, this is the code that interprets the song “script” and transforms it into a WAV stream.
  • Theme song (5148 bytes): Created by Ryan Malm, it’s exported from Soundbox online player.
  • SFXR player lib (2637 bytes): Minified form of the original source code here, this code allows playing SFXs based on a list of settings
  • Initialization function (466 bytes): Creation of the music player and the WAV stream from the song script.
  • Sound data for SFXR (484 bytes): 5 different sound effects represented by SFXR instructions (Explosion, Bullet, Missile, Super Explosion, Start Game Beep)
  • SFX playback functions (359 bytes): Preload Audio objects from SFXR sound data and allows easy playback.
  • pRNG functions (719 bytes): Functions to generate random numbers, including the seedable pRNG.
  • Keyboard input routine (533 bytes): Some hooks around keypress and keydown to allow polling for the state of a key or add a listener function.
  • Shape renderer (1765 bytes): Given a canvas rendering context, a set of “shape instructions”, a position and a scale value, translate the simplified instructions into Canvas 2D API operations.
  • Mob class (887 bytes): Model the basic things moving around in the world, every Mob has an appearance, speed, and position in the x and y axis. This class also includes functions to update the mob, destroy it and check collisions with other mobs, as well as the creation of explosions.
  • RAF function (401 bytes): Function that allows hooking other functions into an animation frame, doing the fundamental calculations for the elapsed time between frames which are used to (try to) keep things running at a constant speed regardless of where they are run.
  • Collision functions (177 bytes): Simple collision checks based on the Manhattan distance between two mobs and their size.
  • Game Loop (1952 bytes): Keeps tracks of different list of mobs, used for both updating them on each animation frame, as well as rendering them on screen. It also keeps tracks of the animation-based Timers
  • LCD-like number rendering (805 bytes): Allows drawing any number as an LCD-like display.
  • UI Rendering (1371 bytes): Depending on the current state of the game, might draw the loading message, or the title screen, or the HUD including the scores and the current wave, or the Game Over message.
  • Enemy Factory (2318 bytes): Contains the stats for the different kind of enemies, as well as function to create groups of them in a given initial setup. For example you can request the factory to create 5 mines in horizontal formation at y = 200
  • Player Ship class (2356 bytes): Extends Mob, has special checks on its update function to simulate inertia as well as handle the practical “3d” effect when moving around and keeping the player ships on-screen. Of course, it also includes functions to control the movement of the ship using the keyboard (the actual keys that are used are received as a parameter, which means there could potentially be more than 2 players on screen). Also allows firing missiles, and keeps track of a player’s score.
  • Enemy class (1208 bytes): Extends Mob, has a simple “reaction” model which allows it to potentially fire a bullet at the player each x milliseconds. The speed of the bullet on each axis is calculated using the arc-tangent between the target and the enemy. The target is selected from the list of players (the closest one)
  • Star class (304 bytes): Extends Mob refining the destroy class so that a new star is created at the top when a star is destroyed.
  • Planet class (366 bytes): Extends Mob defining a special render function which draws a circle filled with a gradient based on the 2 colors and rotation of the planet.
  • Explosion class (928 bytes): This class is similar to Mob, but explosions have no speed (just a position). It’s designed to progressively draw an explosion on screen, based on the “run time” and “size” parameters, the size and color of the circle to be drawn are determined by the “progress” of the animation (a value growing from 0 to 100, based on the accumulated render time and the total run time). When fading, it substracts from the drawn circle creating a growing “hole” inside of it.
  • Shape definitions (2487 bytes): A dictionary of lists of drawing instructions to be interpreted by the Shape Renderer, all Mobs have a reference to a shape definition, used in the game loop
  • Game Start function (683 bytes): Plays the theme song, creates the player ships and starts a timer for wave generation. Called by the title screen and the enter key handler (for restarting the game)
  • Enemy Wave Generation (1947 bytes): Several functions containing the logic to create a new “wave” of enemies. Levels are made of waves generated every 3 seconds, this component decides what enemies will be spawned on each wave, and under what behavior. Makes extensive use of the seeded pRNG, as well as the Enemy Factory. Also creates the planets.
  • Enter key handler (320 bytes): Used to control the game state from the title screen and game over status, into the “in game” status.
  • Game state machine control functions (628 bytes): Transitions into the different game states (title, game over and “in game”)

Coming up next, final postmortem and future of the game!


ArcherFire: Duet of Aces – js13k 2018 – Part 2

JS13k 2018 has gone by! this is the second of a series of posts detailing my journey, as well as the structure of the game I built. You can play it online here!

Links to the full series: part1part3postmortem

Day 4

First thing I did was fixing the build scripts since I really needed to know how I was doing vs the 13KB limit (last year I spent a lot of time by the end of the time-frame, removing things). I figured out the build problems by checking the script for Lost of Asterion; I had to replace a dependency (gulp-uglify) with the ES6 ready version (gulp-uglify-es) since I was using ES6 features in my code (cannot live without arrow functions now). The zipped archive was 5.36KB, and I had 46 hours to go.

I created a list of priorities in Trello, as I said there was a game there already, so what was left was polishing some rough edges and add fancy stuff. The last missing core thing was making the levels consistent (that is, they should be the same every time the player plays). Of course, the trick because of the size restrictions is not having the levels hand-designed but rather using a seedable (and small) pRNG, I ended up using an implementation of  Park/Miller LCG based on this.

function LCG(s) {
  return function() {
    s = Math.imul(16807, s) | 0 % 2147483647;
    return (s & 2147483647) / 2147483648;

I seeded it with 13312, and it’s used only for the enemy wave generation.

Another annoying thing I was pending fixing was replacing the temporary setTimeout based timers with something that relied on the game update cycle instead so that the game wouldn’t go bananas when the animation was paused (say because the game’s tab became inactive) but the timers kept running. I added a simple function to the RAF loop to keep track of a list of timers on every frame update, reducing a timeout value by the update delta, and executing a callback when it reached zero.

Next up was showing the “current wave” in the UI, so that players could have a sense of progress besides the score so they could brag about being able to reach wave X. This was also used to increase the difficulty of the waves, so the further the player is the harder the enemies and the shorter their reaction time (so they shoot more bullets)

There were some weird issues where mobs were being “killed” out of nowhere, I thought this may be due to the way they were being sliced out of the lists during the update phase which might cause the wrong mob to be deleted. I changed it so that when a mob’s update function deemed it necessary for the mob to be killed, it is marked and then all the marked mobs are deleted, instead of doing it on the spot. It seemed to work.

Also added some cosmetic changes on the explosion SFX, changing the colors so that it looked a bit darker and different when fizzling, and a scaling effect so the ships would look like they were “landing” on the game (but it didn’t look very good)

Finally, continuing with the idea of adding a music track, I asked on the js13k slack and was lucky to have Ryan Malm offer to create a track for the game, as long as I could set up SoundBox on it.  So I did that and added one of the sample tracks.

Screen Shot 2018-09-18 at 10.34.22 PM
SoundBox in action

Day 5

The final day of development was long, but not really too crazy compared to last year.

I proceeded to add more variation to the different enemy formations, adding the following:

  • Enemies coming from below
  • Horizontal row of mines
  • Vertical row of mines

I also did the best I could to enhance the appearance of the turret “platforms” and the mines.

Designing the appearance for the enemies

Added some planets to the background, they are a circle filled with a gradient, their generation is tied to the wave generation so they serve as milestone markers to see how far you’ve gone (so far I have only been able to reach the second, purple planet, in my highest score)

Did some playtesting and balanced the difficulty a bit, then, since the game bootup was a bit crappy, I added a “loading” screen to cover the process of converting the soundbox script into a WAV stream, in turn, I also added a simple title screen with the name of the game, some credits, and instructions. This required adding some “mode” handling to the game and a simple state machine.

Was getting close to midnight when I got the theme song by Ryan, it was awesome! because of time constraints, it was a bit short (about 15 seconds long) but it did a great job at enhancing the atmosphere of the game.

It should be noted that this 15 seconds track, including the whole “library” to play it, is 2.5KB of compressed source code. Compared that to 361 KB for the OGG export. It’s really wonderful.

I did some work on the player bullets, changing them from red balls to missiles, using a different sound effect for them, and throttling the fire rate so it was more controlled and predictable. Also, since I still had plenty of space, added sounds for the explosion when a ship was destroyed, and a beep for starting the game.

Continued with small tweaks, removing the “ships landing” scaling effect which didn’t really look too good, changing the keybindings for the “down” key for player 2 to be “5” instead of “2”.

The game was almost ready to ship, I did some basic CSS styling for the containing page (black background, centered canvas), but more importantly scaling the canvas to 100% height so that it looked good on most horizontal display cases.

I hesitated a lot, but in the end, decided to jump into allowing the player to restart the game without having to refresh the page when dying. Anyone who has participated in a jam knows how tricky it can be to reset the game state, especially if you didn’t design for that in advance. But I went ahead and did it, and I think being able to restart quickly  became an important part of the game (and makes it look much more polished)

As part of the final playtesting, I added “shield” to the ships so the player can take 3 hits before dying instead of exploding instantly, and increased the acceleration so it’s easier to dodge bullets. I also fixed an issue with the Numpad not working in Safari and Firefox


Next up, a view of the complete structure of the game, and then some final thoughts!