The ROOTWAR arena: ranked duels and the ELO system

Duel rules

In the Arena tab, click “Find a duel”. The server pairs you with an opponent of similar strength, then a VS screen runs a 3-second countdown. The duel is played in rounds:

• each round both players receive the same puzzle at the same time;
• the first correct answer wins the round;
• a wrong answer locks you for 1.5 seconds, so guessing does not pay;
• after 20 seconds without a correct answer, nobody scores;
• first to 3 rounds wins. After 7 rounds the higher score wins, and a tie is a draw.

The answer is never sent to players before the round ends, so inspecting network traffic gets you nowhere. Guests can play in the arena just like registered accounts.

Matchmaking and disconnections

Matchmaking first looks for an opponent within ±100 ELO, then widens the window by 50 points every 5 seconds of waiting. You cannot be paired with the same opponent again within 2 minutes of a duel, which prevents friends from farming each other.

If your connection drops you have 15 seconds to come back: the duel resumes exactly where it was. After that the match is lost by forfeit. During a duel you can send emotes (one every 3 seconds): “GG” is free, the others are unlocked in the shop.

ELO rating and tiers

Everyone starts at 1,000 ELO. After each duel the points exchanged depend on the gap between the two players: beating a higher-rated opponent pays a lot (up to 32 points), beating a weaker one pays little, and a draw pulls both ratings together. Your ELO sets your tier:

Reaching Root for the first time unlocks the “Root” UI theme and the “Root Rank” avatar frame, which cannot be bought. At the end of every season your ELO is pulled halfway back towards 1,000: the best stay ahead, but the race starts again.

Hex and binary puzzles

Hex: copy a six-character code (digits and letters A to F). Case does not matter. Read the code in pairs · A3 F0 9C, rather than character by character, and watch for the classic mix-ups between 0 and D, 8 and B.

Binary: convert an 8-bit byte into a decimal number. From left to right the bit weights are 128, 64, 32, 16, 8, 4, 2, 1: add the ones set to 1. For example 10110010 = 128 + 32 + 16 + 2 = 178. With practice, remember that the left nibble counts 16 times its value: 1011 = 11, so 176, then add the right nibble 0010 = 2.

Decryption and sequence puzzles

Decrypt: a 5 to 7-letter word from hacking vocabulary has been encrypted with the Caesar cipher, shifting every letter by N positions. Shift each letter N positions back to recover the word. You rarely need to decode it all: the first two or three letters are usually enough to recognise the word.

Sequences: five numbers, find the next one. There are three families:

• arithmetic: add the same value every time (3, 7, 11, 15, 19 → 23);
• geometric: multiply by the same value every time (2, 6, 18, 54, 162 → 486);
• Fibonacci-like: each term is the sum of the previous two (2, 3, 5, 8, 13 → 21).

Start with the difference between the last two terms: if it is constant you are done; otherwise try the ratio, then the sum.

The ports puzzle

Twelve port numbers between 1 and 99 are shown; click every one divisible by the given number (between 3 and 9), then submit. There are always between 2 and 5 correct ports, and order does not matter. A few mental-math shortcuts:

• divisible by 3 or 9: so is the sum of its digits (87 → 15, divisible by 3);
• by 4: half of the number is still even;
• by 5: it ends in 0 or 5;
• by 6: it is even and divisible by 3;
• by 7 and 8: learn the multiples up to 98 and 96 by heart, it beats computing.

Improve fast

1. Do not guess: the 1.5-second penalty often costs you the round.
2. Keep your hands on the keyboard: the answer field is focused automatically, submit with Enter.
3. Chain duels: puzzles are drawn at random, so consistency matters more than one brilliant round.
4. Aim for the top: ELO has its own leaderboard, and each season’s best players are rewarded (see seasons and rankings).

Frequently asked questions