microtony's entry for Riot Games API Challenge 2016
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Splash Art Puzzles

microtony's entry for the Riot Games API Challenge 2016

Play now!

How to play

Sliding puzzles made of splash arts! Featuring 8 different levels (difficulties), click on tiles adjacent to the empty space to solve it. Unlock new skins and the next difficulty for the champion by solving the highest unlocked level. Alternatively, verify your League of Legends account to unlock levels and skins using your in-game Champion Mastery levels!

Guests starts with Level 0 for every champion. Verification can be done by adding a code to one of the mastery pages. Levels 6 and 7 can only be unlocked by solving level 5 and 6 respectively until Champion Mastery levels 6 and 7 are introduced. Skin unlock levels are generated pseudo-randomly.

  • Level 0: 3 x 2
  • Level 1: 4 x 3
  • Level 2: 5 x 3
  • Level 3: 6 x 4
  • Level 4: 7 x 4
  • Level 5: 8 x 5
  • Level 6: 9 x 5
  • Level 7: 10 x 6

Sample Level 7 puzzle (Lux default skin)



Main technologies used: CSS (Bootstrap framework) and Javascript.

There is only one static HTML page. The Sliding Puzzle Game is written in Javascript. First of all, the tiles are randomly shuffled. Not all arrangements are solvable (50/50 chance), so puzzles are regenerated until a solvable one is obtained. This article Solvability of the Tiles Game explains the conditions of a solvable puzzle.

To render the puzzle, each tile has an HTML data attribute which stores the current position. SCSS is used to generate the necessary styles for placing the tiles into the correct positions according to the position data attribute and level. Compass.app by KKBOX is used to generate and minify the CSS.

The game is optimized for mobile devices.


Main technologies used: Node.js + Express + MongoDB

The server exposes API endpoints for retrieving users' info (levels and League of Legends account connect status), and to unlock levels.

To store user progress, a new user is created when a guest solves the first puzzle. The ID of the user is then saved into the session. Both users and sessions are stored in a MongoDB database. Levels that are unlocked by solving puzzles are stored in a subdocument called manual, while levels that come from the user's Champion Mastery level are stored in the account subdocument.

A sample user document is shown below:

    "__v" : 13,
    "_id" : ObjectId("572c40893c7c58c8351f33d0"),
    "account" : [ 
            "champion" : "Darius",
            "level" : 1,
            "_id" : ObjectId("572c8fed88c214804afdb564")
            "champion" : "Zilean",
            "level" : 1,
            "_id" : ObjectId("572c8fed88c214804afdb565")
    "connected" : true,
    "manual" : [ 
            "champion" : "Ahri",
            "level" : 5,
            "_id" : ObjectId("572c8fed88c214804afdb55d")
            "champion" : "Fizz",
            "level" : 2,
            "_id" : ObjectId("572c8fed88c214804afdb55e")
            "champion" : "Ezreal",
            "level" : 7,
            "_id" : ObjectId("572c8fed88c214804afdb55f")
            "champion" : "Lucian",
            "level" : 1,
            "_id" : ObjectId("572c902588c214804afdb568")
    "name" : "microtony",
    "playerId" : 20545469,
    "region" : "NA"

Once connected to an League of Legends account, the Champion Mastery levels will be automatically updated when the user opens Splash Art Puzzles. Cache time is set to 1 hour.


You may use your favorite IaaS or PaaS such as Heroku and Openshift.

  • Choose a Node.js gear and add MongoDB to it.
  • Checkout the repository locally.
  • Add the Heroku / Openshift Git remote
  • Merge the repositories
  • Run npm run download to generate the static Champion data files
  • Push the code

There are three additional environment variables that you need to configure:

  • API_KEY: Your Riot Games API key
  • UNLOCK_SECRET: A secret (long random string) used for generating the code for verifying LoL account.
  • SAP_SECRET: A secret used for encrypting session cookies.

Heroku: heroku config:set <Variable>=<Value>

Openshift: rhc env set <Variable>=<Value> -a <App_Name>


  1. There is no anti-cheat mechanism, meaning that users can modify the DOM with developer tools to unlock skins and levels.
  2. Splash arts currently available via Data Dragon are right-aligned. Therefore, I made the bottom-left corner the empty space, as opposed to the usual bottom-right corner. Repositioning of the empty space can be reconsidered when the new centered splash arts becomes available.