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Previous updates

. Main page updated to become an "about me" page. A lot of other pages are also updated.

Welcome to my site,! You might know me as chaotic_iak online, or Ivan Adrian Koswara in real life, or Sky in furry circles.

This is my personal website. You can navigate through the main pages of the site through the menu above. Read on for information about me and how to contact me.

About me

Real life and academic

My full name is Ivan Adrian Koswara, although I sometimes drop the middle name (into Ivan Koswara) when it's not needed and I want to use a shorter name.

My pronouns are he/him, but I'm not a stickler about it.

I'm from Indonesia and was born in 1995. I received my bachelor and masters degrees from KAIST in South Korea. Currently, I am a Ph.D. student in National University of Singapore. I am studying theoretical computer science and mathematics, and I have published a few papers.

During my school days, I participated in numerous math competitions. I was a medalist for the national mathematical olympiad (Olimpiade Sains Nasional) and I was a participant in International Mathematical Olympiad in 2012.


Online, my username is chaotic_iak. Sometimes the underscore is dropped. There is a silly story behind this username (see below).

I'm not picky on how you call me. I've heard people calling me chaotic, chao, or iak. I personally recommend chao, but I respond to any of them. Likewise, if you want to pronounce chao, you can use a "hard ch" sound (like the English word chaos) or a "soft ch" sound (like choose).

I'm active in a lot of places online. See below for ways to reach me.

A story about my username

When I was still young, I was a big fan of the Sonic the Hedgehog franchise. Two of my favorite characters were Tails and Cream, and I knew there was something called Chao.

Seems like I already had some fun with words even as a kid. I took them together as "Chao" + "T" for Tails + "C" for Cream, with an "i" to make it a full word, and ended up with ChaoTiC with that capitalization. I added an identifier "iak" (initials of my real name) to give my username: ChaoTiC_iak.

Over time, I realized this reasoning was kind of dumb, but the name had already stuck; I already associated myself with this username. At the very least, I dropped the capitalization so that it wasn't awful to type, leading to my current username chaotic_iak. This mostly dropped the reference to Sonic, although the nickname chao was still sort of derived from there.

(If you're wondering, nowadays I'm a big fan of Pokémon instead. I do still play some Sonic games from time to time, just not as much a fanatic over the series as before.)

Puzzlers Club

One place I hang out the most is Puzzlers Club (PC). It's a community on Discord that started in 2017, as a spin-off of a previous community that had split focus. As per its name, it's primarily focused on puzzles, but it's also a community with diverse other interests (mostly similarly thinky). I am a moderator there.

Puzzlers Club has produced several things:

  • Numerous logic puzzle sets for 24-Hour Puzzle Championship and Logic Masters India. Generally I organized these; you can find write-ups about them on my logic archive.
  • A PC-only event called Logic Showcase, where people are given a prompt to write a particular kind of logic puzzles, and the puzzles are then put up for a vote. I contributed a few puzzles to various installments of this.
  • A PC-only event called Secret Solver, which is like Secret Santa but you write puzzles instead of buying gifts for your recipient.

Unfortunately, it is private. New members need to be vouched/recommended by an existing member. If you saw advertisement for joining PC, such as in past 24HPC and LMI contests, that no longer works.

Puzzles and games

I love puzzles. I solve and write quite a lot of them.

My favorite kinds of puzzles are logic puzzles. Logic puzzles in this case means things like Sudoku and Kakuro: puzzles you can solve without knowing anything about words, or history, or pop culture, or anything like that. I have written a ton of logic puzzles, including some logic competitions, and I've been in the process of filling up my logic archive.

I also enjoy playing "thinky games", specific kinds of video games that are about solving puzzles and challenges. Most often they are puzzle games such as A Monster's Expedition and Baba Is You. While I don't have commercial releases, I have written some free games using PuzzleScript.

I also occasionally dabble in puzzlehunts: events containing puzzles with no instructions, where you have to first figure out what you even need to do. Hunts are done in teams, and I have gone through multiple teams, mainly following where my friends are. My current team is ⛎ UNICODE EQUIVALENCE.


I am a furry. My main fursona is Sky, an anthro Shaymin Sky Forme. I have made several friends as a furry, and I'm known as Sky, the same as my fursona's name.

Besides Sky, I also have several other characters, most of them anthro Pokémon.

I love fluffy and cute things. My favorite Pokémon species are mainly the cute kinds. Likewise, my favorite furry pictures are also the cute kinds.

Contact me

These are some places you can find me online, which includes the most common ways to contact me.

Note: Please do not just say hello. You're welcome to contact me, but tell me how you found me (or this website) and why you're contacting me. Otherwise, you risk having me ignore your message, or even assume you're a spammer and block you.

General online presence

Twitter: @chaotic_iak

I used to use it a lot; nowadays I mostly retweet cute furry and Pokémon pictures.

Cohost: @chaoticiak

After the Twitter buyout in November 2022, I started finding other spaces online. I signed up for Cohost, and now I think it's my main place to post things publicly.


After the Twitter buyout in November 2022, I started finding other spaces online. I got an invite link for Bluesky and set up an account. I haven't really used it, though; I'm just following a few accounts.

Reddit: chaotic_iak

A majority of my Reddit activity is on r/magicTCG; I rarely go to other subreddits.

Chatting platforms

Note: Replace [my username] by chaotic_iak. A little obfuscation to defeat bots.

Discord: @[my username]

A lot of my online activity is on Discord.

I'm in a puzzle server called Puzzlers Club, where I'm a moderator and one of the earliest members. I post a lot of content there; only things that I think are good enough will find their way out the server. That server is private, though.

I'm also in many other servers, but I don't talk much in them.

Telegram: @[my username]

For some reason, I mainly use Telegram for furry contacts, and Discord for other online friends. But you can contact me either way.


My personal e-mail is [my username] Note the ending of the address.

My business/academic e-mail is [my name], where [my name] is ivanak.

I check my e-mails pretty often; you can expect it to be read within 24 hours, and likely less. If I haven't replied by then, either I forgot to reply to your message or it went to my spam folder; try sending me another or contacting me some other way.

Gaming accounts

Logic Masters India: chaotic_iak

I used to participate in a lot of LMI contests. (I still do, although with occasional hiatus.)

My profile has a list of my past performances. It also has some of my authored contests, although I also archive them on my logic archive page.

Steam: chaotic_iak

I play a lot of games and have quite particular opinions about them. Most games I play are indie.

I also often buy games and then don't find the time to play them. Oops.

Nintendo Switch: chaoticiak (SW-6267-2170-3046)

I mainly play games on Steam, but I do also play on Switch. Usually games where a joystick is preferred over a keyboard.

Most of my AAA gaming happens here; a lot of Pokémon, occasional Mario. Sometimes I double-dip on some indie games I love to support them extra.

I don't have any other gaming console and am not interested in getting one.