It's been a few years since I built anything in Elixir so I decided this weekend to refresh my memory.

Rather than build yet another location-based API, I decided to try a game.

Combining super-simple gameplay and Phoenix Channels, I eventually ended up with Snex - Multiplayer Snake.

On page load, you are assigned a random session ID so you can copy-paste the URL and share it with any one to play on the same board.

I've currently got it deployed on Gigalixir.

The performance on the deployed version isn't great due to network latency. Essentially, the game ticks every 100ms and sends an update to each player so if you're moving left then press down, typically the server will process one more left event before your down arrives. There are plenty of blog posts about handling latency, not just in multiplayer online games but also specific discussions on multiplayer online snake. I decided I could either dig into refreshing my knowledge of that or stick with refreshing my knowledge of Elixir and Phoenix. I went with the latter.

github.com/thingsinjars/snex

Operations

1+ players

The aim is to get the highest number possible after using each of your tokens.

There is 1 die

Each player has 4 tokens with different symbols on:

+ − × ÷

Each player rolls the die and the number they get is their starting number.

Lowest score starts. If there's a draw, youngest of those starts.

Each round:

1. Roll the die
2. Choose one of your operations.
3. Perform your operation with the new number and your existing number. Try to get the highest score
4. Discard your operation token. You only get to use each operation once.

Note: When the calculation is a division with a remainder, you can either discard the remainder or continue with decimals, depending on who is playing.

Example game:

2 players.

A rolls 2, B rolls 3. A has the lowest starting number so they start

1. Round 1
   • A rolls a 4. They decide to use their + operation. They now have 6.
   • B rolls a 1. They use their ÷ . They still have 3.
2. Round 2
   • A rolls 6. They use their × . They have 36.
   • B rolls 5. They use their × . B now has 15
3. Round 3
   • A rolls another 6. They've already used their × so they have to either subtract 6 or divide by 6. They use − . They have 30
   • B rolls 2. They + it. B has 17
4. Round 4
   • A rolls another 6! Now they only have their ÷ left. They have to divide 30 by 6. Now they have 5.
   • B rolls 3. They have their − left. B has 14.

B wins.

Variations

• For advanced maths, add in the power and root symbols ^ √
• Try to get the lowest score instead of the highest.
• Try to get the lowest score without going below zero.

For anybody who has a bit of a technical, problem-solving mind (I'm going to guess that's literally anybody reading this), there's a high likelihood that you have not only played with or owned a Rubik's cube but also attempted to solve one using a step-by-step guide.

Notation

Most guides are written using 'Singmaster Notation' where F denotes a clockwise rotation of the side facing the solver, U' is an anticlockwise rotation of the uppermost layer, and so on.

This notation is used to describe not only solving steps but also scrambles when applied to an already solved cube. The following scramble, for example:

L R' D2 U' B D2 F2 D F' L2 F2 R' D' L R2 D U2 L F' L' B2 D U R2 F' D' L' R D2 U

Produces this:

Kana Flick

In seemingly unrelated news, the standard way to type Japanese characters on a smartphone is using a Kana Flick Keyboard.

This style of keyboard groups characters together so that you essentially touch the key to select the consonant, move in one of four directions (or stay still) to select the vowel and let go to confirm. Put that way, describing it takes a lot longer than actually doing it.

Rubik's flickboard

This is a long preamble to say that I was thinking through a new game design the other day when I had an idea about a variation on the kana flick keyboard that could be used to enter Rubik's cube move notation:

Note: It doesn't yet include 'fat' moves (lowercase variations which denote moving two slices of the cube rather than just one), E, S or rotations (x, y, z).

It only works on iOS for now because it was a Sunday-evening sofa hack while rewatching Voyager on Netflix.

Rubik's Flickboard (iOS only)

Every couple of months, we have a Research Week. It's kind of like the well-known Google 20% time but instead of doing it one day a week, we gather up our time and do a week of maps-based hacking. It's totally cross-discipline so we usually gather a couple of developers, a couple of UX and visual designers, a QA and build something cool. In past Research Weeks, I've built or helped build the Alien Easter Egg, Maps Labs and CoverMap.Me. I also built a maps-based JSBin fork called JotApp.

When my partner-in-crime Max started working on the latest version of his jQuery plugin (formerly called jOvi, now called jHERE), I wanted to build a new playground where people could play and build their own maps mashups and hacks really easily. My first thought was to rework the fork of JSBin again and maybe add in a slightly nicer default theme. I wanted users to be able to save to Gists so, seeing as there is already an SQLite and a MySQL adapter, I wrote a Gist adapter which appeared to the application as if it were a database but actually saved to anonymous Gists. The problem was that it was a bit too… heavy.

Don't get me wrong, JSBin is a fantastic project. It just does a lot more than I needed. I didn't need the MySQL adapter, the alternate themes, the localstorage or the user registration. Also, it's a bit too weighty for my phone. When someone tweets a link to a JSBin or a JSFiddle, I usually check it out on my phone and it's not the best experience. Seeing as HERE maps work on mobile, I wanted my playground to work, too. Rather than spend a couple of hours cutting out all the bits I didn't want from JSBin, I decided to spend a couple of hours building my own version from scratch. So, this past Sunday afternoon, that's exactly what I did:

jHERE Playground

It's written in NodeJS on top of express and works nicely on desktop, iPad and mobile.

The project is open-sourced on GitHub (naturally) and can be modified to be a general JS-playground for anything. If you fancy a simple, self-hosted JS hackspace, just change the default HTML, CSS and JS and it's ready to go.