Challenges

What comes when

Besides the 200 levels, Challenges on the title screen serve puzzles that nobody has seen yet. They arrive on a fixed schedule, they are the same for every player, and each has a leaderboard. None of them is one of the 200 levels, and each one stays on our server until its period starts, so there is nothing in the game or on this website to look up in advance.

Days, weeks and months are counted in UTC. A new day starts at 00:00 UTC, a week starts on Monday at 00:00 UTC and a month on the 1st. If a period ends while you are in the middle of a puzzle, you have ten minutes of grace to finish it.

Summit is the top of the ladder: the two hardest boards in our database. The 200 levels stop at 49 moves so that nobody can rehearse these, and each Summit board keeps its own all-time leaderboard.

How the ranking works

Fewest moves wins, and the fastest time breaks a tie. Both numbers are measured by the server, not by your device.

• Moves. The game sends the list of slides you made, and the server replays them on the puzzle with the same rules as the game. Only a list that really solves the puzzle counts, and its length is your move count, so a score cannot be typed in.
• Time. The clock starts when you first open a puzzle and stops when the solve reaches the server. It keeps running if you leave, so open a puzzle when you mean to play it. A solve faster than a quarter of a second per move is kept off the board until it has been looked at.
• Sets. Easy and Medium come as sets of ten and three. A set ranks on the number of puzzles solved, then total moves, then total time, and the time of each puzzle runs from its own start to its own solve, so breaks between puzzles do not count.
• One ranked try. Only your first try at a puzzle counts. Playing it again is practice, timed on your device only.
• No hints. Undo and restart work, and undo removes the slide from the list while the clock keeps running.

A leaderboard shows the top 100, your own rank and how many players there are. Equal results share a rank.

Each first solve also earns challenge points: 10 for Easy, 25 for Medium, 60 for Hard, 150 for Expert, 400 for Master and 1,000 for Summit, doubled when you solve the puzzle in par. In the apps they add up to a weekly leaderboard on Game Center and Google Play Games. Solving the daily challenges seven days in a row, or thirty, earns an achievement of its own.

Signing in

You can open Challenges without an account and play every puzzle for practice. To rank, you sign in and choose a leaderboard name.

• On this website the sign-in is Google’s. The game sends you to Google’s own sign-in page and Google sends you back. We ask only to recognise your account, never for your name, email address or picture, and we never see a password.
• In the iPhone and Android apps ranking uses Game Center or Google Play Games, with no separate sign-in. The apps are covered in where the apps stand.
• Accounts are separate for the website, iPhone and Android, but all three post to the same leaderboards.

You choose the leaderboard name once: 3 to 16 letters, digits and spaces, with a filter that turns down rude and official-looking names. The game suggests one, such as Swift Taxi 482. Your Google or Apple name is never shown.

What is stored

Challenges and saving your progress are the only parts of the game that use our server, and only once you use them. The full list is in the privacy policy. In short:

• A game account: a random identifier with no name or email address. On the website your browser keeps it under the key gl.auth.
• For each puzzle you open: which puzzle, when you started and, once you solve it, your moves and time. Your list of slides is checked against the puzzle and then discarded.
• Your leaderboard name and results, which the leaderboard shows to other players. It never shows your Google account or your game account’s identifier.
• Totals kept with your account so that nothing is counted twice: puzzles solved, challenge points for the week and your daily streak.
• If you are signed in, your level progress (levels solved, fewest moves, stars and achievements), so it comes back on another device. Your hints and settings stay on the device.

It is kept in Google’s data centre in Finland, until you delete it. In Challenges, Delete account removes your name, results and game account at once, while Sign out only forgets the account on that device.

Playing them

Open Challenges from the title screen. The menu shows each tier’s current puzzles and which ones you have solved, and when they end. In the apps you can ask for a reminder once a day, at a time you choose, for when new challenges are out. The reminders are scheduled on your device for the next 14 days only, so if you stop opening the game they stop too, and nothing about them is sent to us.

The challenge puzzles use the same rules as the levels, so the puzzle guide applies to them as it does to level 1. Stars are not awarded in challenges. Rank is.