24 hour janken - 1st world championship (janken for 24 hours)

Entry to 24hour janken was closed

We will announce the ranking of all participants on Tue. Jan 26th.

"24 hour janken" was created and developed by nikoli.com. It is a championship with janken (the well known rock-paper-scissors game), which is a popular game among Japanese. We already had several janken championships on the Japanese page. This time we are holding the first 24 hour janken world championship.

Please participate with the entry form at the bottom of this page.

The rules for 24 hour janken


First we will explain the janken game. In janken, you and a rival simultaneously show (form) one of the janken shapes with your outstretched hand. So, each of you show one of the three shapes (rock, paper, or scissors) as in the figure on the right. The outcome of the janken game is decided like in the rules in the figure. For example, if you show "rock" and your rival has "scissors," you win. If you and your rival show the same hand (hand-sign), you are tied and there is no winner.

The 24 hour janken rules are as follows. The janken world championship lasts from 00:00:00 to 23:59:59 JST (UTC +9 h) on one date. Input your nickname, hand, and email address and enter with the entry form at the bottom of this page.

You enter the janken championship at your entry time (when you post the entry form). Your entry time is expressed in JST (Japan Standard Time, 9 hours ahead of UTC). The year, month, and day will be ignored in the entry time. If there are several entries at the same time (the same hour, minute, and second), they are eliminated from the championship. The entrants who are not eliminated become challengers and challenge the present "king" by the janken rules.

When the challenger wins:

The winning challenger assumes the throne, and this new king will face challenges from the following entering challengers. The (new) king keeps the hand for the next challenge (that input in the entry form). The hand (rock, paper, or scissors) cannot be changed.

When the king wins:

The king has defended the throne and stays on the throne. The challenger is eliminated from the championship.

When it is a tie between the king and challenger:

The king and the challenger both leave the championship. There is now no king on the throne.

When the throne is empty:

The next challenger will become king and assume the throne by default.

When the king is on the throne at 23:59:59:

The reign of this king is from the throne was assumed (the entry time) to 23:59:59.

Among all who were kings during the 24 hours, the person with the longest reign is the champion. Similarly, the 2nd place, 3rd place, and other places are decided by the length of a reign. If there are several reigning kings with the same length of reign, the earlier participating king will get the higher rank.

EntrantsHandsEntry times

Here is an example. Entrant A assumed the throne at 01:23:35 (the entry time) because the throne was vacant at that time. Entrant B challenged the king (A) at 01:23:45 and B's hand beat A. Then B assumed the throne as king. As a result, A was the reigning king for 10 seconds (from 01:23:35 to 01:23:45). The next challengers C and D were eliminated because they entered at the same time. So B defended the throne successfully at 01:25:50. Challenger E entered at 01:30:03, and the throne became vacant because B and E were tied in the janken. Finally the reign of B was for 6 minutes and 18 seconds (from 01:23:45 to 01:30:03). Then, at 01:32:17 challenger F entered, and assumed the throne at 01:32:17 by default.

Entry deadline

Mon. Jan 18, 2016 3:00(UTC)

Result announcement

Tue. Jan 26, 2016

We will announce the ranking of all participants, by nick name. We will also announce the countries where the prizewinners come from and some of the comments we receive.


Duplicated entries from the same email or IP address are invalid. Only the last entry from one address will be considered the valid entry for that person.



nikoli.com original T-shirt

2nd to 5th place

Sudoku Origami

Original T-shirt

nikoli.com original t-shirt

Sudoku Origami

Sudoku Origami

Entry form

Acceptable letters and characters:

ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789@.+-_

Nickname Required

Please make your nickname 2 to 24 characters long.

Your country Required

Please input the name of your country, 2 to 60 characters.

Email address Required
Hand Required

Do you want notification of the game result?

We welcome any messages!

Maximum length, 500 characters.

Complete all the items in the form above and click the Entry button. We will confirm your entry in an email message.