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Global Game Jam 2017 - E.M. Wave Jammer: Release Announcement and Post Mortem

Jan. 22, 2017, 1:42 a.m. Behind the Scenes Gamedev Product Release

This year, I've developed the game E. M. Wave Jammer. It is the world's first telephone game in Global Game Jam, which is playable by dialing a telephone number.

I FUBAR'd in last year's game jam. Fortunately, I did much better this year.

This game is for entertainment only, no political message intended.

Play Now

For Hong Kong SAR phone numbers, dial 54839953. For non-Hong Kong SAR phone numbers, dial +85254839953 with skype. We do not accept international non-skype calls to save our operational cost. This game has Cantonese(Press 1), Mandarin(Press 2) and English(Press 3) version. Please notice that this phone number is temporary. It will be changed after I've finished setting up my phonesite.


The game happens in Japan during Cold War era. In the game, North Korea is using advance electromagnetic waves technology for sending signals to Cuba. They are plotting to attack Japan. In the game, the player plays as the role of the commander of telecommunication department. The player is responsible for jamming the signals between them.

For the ease of command, Japan is divided into 6 zones. The electromagnetic waves from North Korea will propagate via zone 1, zone 2, zone 3, zone 4, zone 5, zone 6, all the way to Cuba.

The player is required to use limited amount of electricity to build jammers. Electricity are consumed for building the jammers. No electricity is required to operate the jammers. The more electricity you spend to build a jammer, the more powerful it is. For example, a 5W jammer can attenuate the signal by 5W.

The remaining non-attenuated signal will become military information end up on enemy's hand. When the information level reaches 100%, you lose. The information level is increased by the Wattage of signal received divided by the Wattage of signal sent. There is no way to reduce the information level.

The player starts with 20W of electricity. To generate electricity, generators have to be built. They generate electricity when signal pass thru its zone. For example, a 5W generator will cost 5W to build, and generates 5W of electricity.

Each zone can only have one structure(e.g jammer, generator). New structure building on a zone with existing structure will demolish the existing one. Structures cannot be sold.

After wave 6, there will be Accelerated E.M. Wave signal. It is able to bypass Zone 2, 4, 6. It is sent via Zone 1, 3, 5 to Cuba.

After wave 11, there will be Narrow-band E.M. Wave signal, which includes low frequency E.M. Wave Signal and high frequency E.M. Wave Signal. Ordinary jammers are half as effective against these signal compared with other signals. Therefore, the player is able to build LF Jammers and HF Jammers to defend against these signals. A 10W LF Jammer can attenuate LF Signal by 20W, Ordinary Signal by 5W, and cannot attenuate HF signal. A 10W HF Jammer can attenuate HF Signal by 20W, Ordinary Signal by 5W, and cannot attenuate LF signal.

After wave 16, there will be E.M. Wave from Cuba to North Korea, which propagates via Zone 6, 5, 4, 3, 2, 1 to North Korea. Accelerated E.M. Wave from Cuba propagates via Zone 6, 4, 2 to North Korea.

After wave 21, there will be FM Signal. FM Signals is immune to Ordinary Jammers. It makes non-LF, non-HF FM waves very troublesome to be dealt with because they couldn't be attenuated by ordinary jammers. Yet, HF and LF jammers are only half as efficient to deal with non-LF, non-HF waves.


Before the Jam, I've developed the hardware Dinbo Prototype B as well as its library libdinbo. I've also made a template for developing any telephone system based on this library.

In addition of the telephone system, I have also practiced using LMMS, Labchrip, Audacity, SoX, just all of the software that I planned to use. I also planned to practice Aegisub for making video subtitles. Unfortunately, I didn't have enough time and the Jam day had come. :(

First Day

Just like the last year, the 48 hours game jam spanned across three days.

In the first day, I've arrived at the venue, before the event started, I've found a bug on the library of Dinbo Prototype B that made it failed to detect DTMF touch keys properly. Fortunately, I fixed it right before it started.

After that, I've listened to the briefing. After the theme Waves was announced, I came up with this game design quickly. Since I was working solo in this jam, this process went way quicker than the jam of previous year. :)

Here is a photo of my game design document. As you see below, it is only one A4 page. It is poorly-organized because I'm the only intended audience of this document. :P

Design Document of E.M. Wave Jammer

Some of the features are strike'd out at the design stage because I foresaw that it couldn't be completed within 48 hours.

Here is a photo taken from day 1 of the event. Sorry for phone camera quality:

Day 1 of Global Game Jam 2017 in Hong Kong Jam site

There were many jammers in our Jam site, and the Hong Kong SAR was the 8th largest out of 700+ jam sites all over the world in 2017!

With the experience of last year, I won't sleep on-site because I couldn't. At the end of the day, I went to home and took a rest.

Second Day

Although I slept much better than last year, I still didn't sleep enough. Therefore, I woke up late. I started programming. Feeling dizzy, I took a nap after an hour of development. Then I woke up again and continue. To save some traveling time, I decide to jam at home this day because I was solo and I didn't need to go to the site to collaborate with my teammates.

With software emulation feature of the libdinbo, I was able to develop the game without dialing the phone number. It saved me some cost of calling the number.

With existing code base, the development went smoothly. I managed to implement the game play. After midnight, I started translating the game into Mandarin as well as English. I have also synthesized and recorded some sfx. Originally I also planned to make music and recording the Cantonese voice myself. Considered that I need to prepare for the presentation, I decided to drop these features and went to bed. All of the development works ended here. However, I still haven't deployed it on the Dinbo Prototype B hardware.

Third Day

I (almost) dedicated this day for preparing for the presentation. I decided to prepare for the presentation before deploying it to the hardware. That is because the deadline of submitting the presentation was very tight. And preparing presentation before the deployment can buy me a bit extra time.

I started with recording the gameplay audio using the voice log function of the libdinbo in its software emulation mode. It went quite well and I've recorded a 9 minutes audio. I had cut down the audio to 4.5 minutes.

Then I asked the volunteers about the time limit of presentation. Turned out that each team would only be given two minutes to present their game. Well, I thought that I had 5~10 minutes. :/

After that, I further cut down the audio to 1.5 minutes. Even the gameplay instruction were removed.

So how did I explain the gameplay? Simple. I used Libreoffice Impress to make some presentation slides to visualize the game play frame by frame. Then I played the gameplay audio and used vokoscreen record the voice and the presentation slides. I clicks as I record and play the gameplay audio. After that, I used ffmpeg to trim beginning and the end of the video. Then convert the video format to webm. Here is the demonstration video in Cantonese.

After that, I prepared another powerpoint file. I planned to use the powerpoint before playing the demonstration video.

Everything went well, except that the deadline was very tight. I had to do everything I said above within like 3~4 hours. Then I uploaded my video to the website of Global Game Jam and sent the powerpoint to the staffs. After that, I have deployed my program to the Dinbo Prototype B hardware.

Here is the presentation session(the guy who is presenting in the photo is not me):

Day 3 of Global Game Jam 2017 in Hong Kong Jam site

It didn't went very well when it was my turn. I thought that I could access a presenter's mouse so that I could show my powerpoint with animation. I thought that I could click the powerpoint myself. Unfortunately, the presenter's mouse wasn't working somehow. Then the staff of my jam site just random clicked his mouse, causing the slides shown up earlier than it was supposed to be shown. After that, the staff was trying to click on the gameplay demonstration video link inside the last slide of my powerpoint. But he forgot to enter presentation mode and couldn't click on the link. It looked very bad for the audience. :/

Nevertheless, the gameplay video was found to be funny by many fellow jammers. I enjoyed their laugh and applause at the end, and I earned a certificate of participation. :)

After that, I have introduced my final year project to my fellow jammers. Then I have interviewed some of them about my project. That is helpful for me to improve my final year project. :)

Finally, it was the closing ceremony of the event. As I have expected, I got no award because I'm solo. Apparently the sponsors of our site is reluctant to give out awards to solo teams. :P

Anyway, I have completed the game during the 48 hours. I have proven that libdinbo is working and I have shown my final year project to others. It is a great success compared with the previous jam.


After the jam, I have talked about the event with people from other jam sites via the Internet. Someone who joined the site of Tokyo University of Technology shared an interesting photo of the site(photo used with permission by the copyright holder of the photo):

Unity Ramen, Salt Flavor with No Bug

Right. That's "Unity Ramen, Salt Flavor with No Bug". Here is the blogpost of the guy who have taken this photo. He leaded the development of the game Super Smash Tokyo in this event.

Apparently the jammers in Tokyo University of Technology site had more fun than we do. Instead of giving out awards to well-performing teams, they had a pizza party! And the award was the game itself that the jammers developed. It is a better match to the sprite of Game Jam.

What Went Well

I'm performing much better in this game jam than the last one. And this year is much more fun for me. Here is what went well:

  • Developed the first telephone game in Global Game Jam in the world! :D
  • Well-practiced before the Jam, making rapid development possible
  • Good time management
  • Being healthy after the jam
  • Completion of game within 48 hours
  • Did some public relation stuffs for my Final Year Project

What Went Wrong

  • Feeling alone. It's kinda sad to see everyone were working together, while I was working alone. Dinbo Prototype B is a part of my individual final year project. I had no choice because if I worked with others, my professor might think that the Dinbo Prototype B was developed by my teammates. :(
  • Less time to socialize with others compared with last jam(because I am solo. I couldn't rotate with others. I was busy working on my game almost all of the time)
  • Presentation screw up - not my fault. But I was still the one who got blamed by the audience :(

Notes to Future Self(May not be true for everyone)

  • Do not jam alone. It feels sad. :(
  • (for Hong Kong site only)Do not use powerpoint for presentation. Just use a video.
  • Perhaps try other jam sites. Global Game Jam is about the experience. It may be interesting to try out the Macau SAR one, the Zhuhai, Shenzhen or the Guangzhou one. And I think I can reach these sites within a few hours.
  • Perhaps try to collaborate with some internet guys from other jam sites. That could be fun. :)

Overall, The Jam of this year went pretty well. And it was a quite memorable experience. :)

Beyond the Game Jam

The Game Jam of this year is very special for me. It has some strategical value. As you may have noticed in my previous blogpost, Dinbo Prototype B will be a successor of the existing telephone system, Dinbo Prototype A. Dinbo Prototype B will be used for the following purposes:

  • Main purpose: Final Year Project
  • Side purpose: Upgrading the whack-a-mole game into a phonesite(you might noticed that the whack-a-mole phone number is taken down for preparation of this upgrade)

This game jam helps improving the code base for Dinbo Prototype B, particularly, the internationalization functionality of the code base was enhanced during the jam. In addition, it's also a good way to test whether the entire system works. If a game can be developed for this system, then it would definitely be possible for me to develop my final year project using the same system.

That says, my mission of Global Game Jam 2017 is accomplished. Now I got to work on my final year project as well as my phonesite. :D

Want to read more? A parallel jammer in Japan had made a blogpost of his game - Super Smash Tokyo

Epic Failure in Global Game Jam

Feb. 7, 2016, 2:25 p.m. Gamedev

As you might knew, I've joined Global Game Jam last weekend. It was a, well, interesting experience. I learned a lot. :P

I thought that I was well-prepared for the jam.

Months before the jam, I've developed the game Half N' Half within 24 hours as a practice of gamedev within very limited time. The project went well.

Later, I've joined Ludum Dare 33 compo and developed Poopie: The Flying Monster within 48 hours. The project went well too. The rating isn't great. But at least it's completed within the time limit. I even got a few hours of spare time.

A few days before the jam, I started preparing for it by playing around with HaxeFlixel.

Unfortunately, the team that I joined didn't complete the game What's life in the jam.

What happened?

The Global Game Jam is a 48 hours event that require me to attend to the jam site physically. On the jam site that I joined, The 48 hours spanned across two days, two evenings, beginning with an evening.

First Evening

In the first evening, we were supposed to form teams. Being an self-taught amateur game developer, I went to the site alone because none of my friends was interested in the event.

Right after the theme Ritual released, I didn't have any idea in my mind. Therefore, I walked around in the site to check whether there was any interesting idea I wanted to work on. Then I found a group with such an idea. Then I joined them as an artist. Since they decided to use pixel art, and I had no experience on it, I did programming instead of art, tho.

The team had nine members. It includes 4 programmers, 4 artists and 3 game designers. One of the game designer was also an artist. One programmer was also an artist.

Right after I joined the group, the game designers argued with each other for exceptionally long period of time(like 5 hours+) over an idea. Being impatient, I asked them to gave me something to program or give me some art to work on. As you know, as long as a part of the game design is settled down, programmers and artists can start working on it. This would allow programming, art and game design to perform concurrently, which will definitely save time. Surprisingly, one of the game designer told me that we can't work on it until the completion of game design. He even insulted me by saying things like "apparently you're the sort of people who write articles in exam without thoroughly planning it". To avoid escalation of the tensions, I shut up. Somehow I didn't leave the team.

During the design process they somehow decided to use despite I strongly object to it. Out of four programmers, none of us had worked with before. Obviously wasn't the choice if we want to complete the game. That is because we would need to spend a few hours to figure out how does the library work. Interestingly, one of the game designer suggested that the spirit of a game jam is to experiment with stuffs.

That game designer is indeed pretty interesting. Apparently, the ideas in his mind isn't very consistent. While he thinks that the spirit of a game jam is to experiment with stuffs, he keep mentioning that some companies joined the jam with many game engines ready. And those companies adapt those engines for the theme. He keep telling us that those games won't get any awards. Implying that he thought that we have a chance for an award. At the moment, what I was thinking was that it's pretty unlikely that our team would get any award because our game probably won't be completed.

After that, I slept on the site by crossing my arms and put on head right above them. The noise of argument of the game design continues. Anyway, at the night the game designers have settled down the complete game design. One of them started working on the Game Design Documentation.

Speaking of Game Designer Document, I found that the document was funny. It was six-pages long. As a reference, behold the equivalent documentation for the game design of Poopie: The Flying Monster, which was a game I developed for Ludum Dare 33:

The document above was designed in like 30 minutes. I wonder how come they need to much time to argue about the game design. Who need a long documentation for a 48 hours game? We got no time to waste. Head on the develop the game already!

While I was asleep, I was still semi-conscious because the sleeping environment was very poor. The light above my head was so bright. Sleeping there is a joke for me. I heard something interesting while I was sleeping. That game designer told another teammate that I was not clever to suggest to work on an idea before it's completely designed. He said that he will "reeducate" me some time later. It was pretty funny for me. I don't see arguing over simple matter for a long time in a 48 hours game jam is a good idea. The longer they argue, the less time we got to develop the game.

First Day

The next day, as expected, the programmers, including me, have spent a lot of time on figuring out how does work without working much on the functionality of the game. We also setup stuffs like Slack, git, etc for the purpose of collaboration.

One of the programmer started reading the game design documentation. I haven't read it. Just by skimming thru it, I found that it was very long! What I knew was that the game is a platformer. I hate reading long stuffs. Therefore, I just wait for other programmers to read the document. :P

One of the funny thing about the game designer is that he got work to do that day. He wasn't available in the site until evening. Fortunately, we didn't need to understand the document because our progress on figuring out how does work was too slow. :P

Second Evening

The game design guy was back. One of the programmer who have read the game design documentation asked for clarification. Turned out that the documentation was misinterpreted. It was really funny. The entire purpose of the documentation is to specify the whole game design. How come it is worded ambiguous enough that it can be misinterpreted? This evening, the game designer seems to have lost his coolness that he had in last evening.

Still, our progress was very slow as of the evening. We only got a character walking with semi-working ladders. Then I decided, with permission of other programmers, to switch to HaxeFlixel myself as a backup plan. Just in case they couldn't make it work with phaser.

Meanwhile, the game designers argues on the design of the game again. It doesn't matter anyway because we didn't program to a point that game design matters.

Then I tried to sleep at night again. Well, again, it's a joke. Since the lighting of the site is too bright, I slept in a couch of a garden near the site. That place was dark enough for me to sleep. In the midnight, a mosquito flew over my ear and woke me up. I couldn't sleep after all.

Second Day

In the second day, I was exhausted of not having enough sleep for two nights. I keep saying "I'm very sleepy" without helping much on the team. Fortunate enough, the other two programmers somehow managed to make ladders, characters and infinite world work. Out of tiredness, I was switched from proactive programming mode to on-demand programming mode. That day, I only programmed when I was asked by other programmers. I was probably sick since this day. But I didn't aware of it. And one of my groupmate started complain me of keep saying I'm being tired, I did find it being offensive. Anyway, I tolerated it.

At the end, we did get a sort of working game. At least it's playable. But it's nowhere from being complete. And somehow I and the groupmate who previously complain me of saying being tired ran into an argument. It was weird. I have a feeling that it was ok for me to be insulted, but it was not ok for me to insult others as a defensive measurement. It was pretty difficult to get along with the game designers in the team. :/ I was getting along well with other programmers and artists, tho.

What Went Well

  • Collaboration between programmers are good. With git, we're working on the same piece of code at the same time without much conflicts.
  • Slack. We share link and resources efficiently.
  • Socialized with a few other programmers in another team as well as some in my own team.

What Went Wrong

  • Incomplete game
  • Poor time management
  • Too many game designers
  • Unrealistic goal
  • Too many arguments over team members
  • Use of unfamiliar library

I and probably other programmers in the team did foresee these issues at the first evening. It's sad that we couldn't do anything on it at all. I regret that I didn't leave the team in the first place.

Notes to Future Self(May not be true for everyone)

  • Never sleep on site. Sleeping at home is a much better choice.
  • Join a team with less members
  • Join a team without, or with only one game designer
  • Consider jamming alone. I have been working well alone :P
  • Leave a team as soon as you found that it isn't suitable for you

Aftermath: Severe Illness

Right after the jam, I found myself suffered from severe illness. I caught cold and I got fever. :(

The fever is now gone. But I'm still having a cold. And now I need to sleep like 15 hours every day. That's why I made this blogpost so late. :(

Alright! After I get well, I'll continue to work on Cellphone Diver!

[WIP]Cellphone Diver - Result Scene

Jan. 20, 2016, 10:06 a.m. Cellphone Diver Gamedev WIP

Just implemented the result scene of Cellphone Diver!

Screenshot of Cellphone Diver Result Scene

As shown on the screenshot above, the result scene shows the number of snail collected, earning contributed by the diving depth, diving time and the total of three.

Next task: Implement upgrade store!

[WIP]Cellphone Diver Prototype Update: Version 0.0.2

Jan. 15, 2016, 2:24 p.m. Cellphone Diver Gamedev WIP

The prototype version of Cellphone Diver is just updated to version 0.0.2!

Screenshot of Cellphone Diver Prototype

What's new:

  • Oxygen Implemented
  • Size of item reduced
  • Implemented new items: bubble, fish, starfish

Click here to play!

[WIP]Cellphone Diver Prototype Available!

Jan. 10, 2016, 3:06 p.m. Cellphone Diver Gamedev WIP

The prototype version of Cellphone Diver is now available!

Screenshot of Cellphone Diver Prototype

Click here to play!