Joachim Breitner

How to play Rock-Paper-Scissors online?

Published 2013-05-11 in sections English, Digital World.

There was an interesting question by ‘Fool’ recently on the StackExchange site for Boardgames: How do you play a game like Rock-Paper-Scissors with friends online? Or any other game where players have to simultaneously submit their moves (e.g. Diplomacy, or Rock-Paper-Scissors-Lizzard-Spock), which, as I just learned, are simultaneous action selection games. While there are websites dedicated to playing specific games, such as, we could not find a generic one that you can use if you, for example, invent your own variants of a game.

So I created one: At you can enter rooms and share the URL with your friends. On the one hand, you have a regular chat room there. But there is also the possibility to enter moves (whatever a move may be to you) and only when all players have done that and marked the move as final, it is shown to everyone. If you want to try it out: There is an integrated, not very fancy Rock-Paper-Scissors-playing bot. Just enter a room, join and say „I want to play!“

Note that this site can be used for more than just for games. Have you ever observed that persons would often want other to express their preference (e.g. where to dine) first to not reveal their own preference, so that they can (or pretend to) change their mind if they would contradict? In such situations simultaneous action selection can be a fairer method.

A technical note: I created this web app using meteor (a JavaScript framework building on node.js and MongoDB that allows for reactive programming), and it is also hosted on I chose Meteor after someone mentioned Firebase to me, which looked very slick, but was not Free Software, so I looked for alternatives. I did not do any cross-browser-testing, and the UI design could be improved, so if you want to help out (or just complain), please use the GitHub code repository and issue tracker.


Fun! Some sharp edges that might deter the casual snooper, but the concept is solid.

What would you recommend as a good intro to Meteor for someone with a haskell background?
#1 Kim-Ee Yeoh (Homepage) am 2013-05-12

can you elaborate the sharp edges? (Preferably as a github issue?)

Meteor is not much haskellish (although reactive programming is somewhat like functional programming), so nothing special here. I learned it from looking at one of the examples and reading
#2 Joachim Breitner (Homepage) am 2013-05-12

Have something to say? You can post a comment by sending an e-Mail to me at <>, and I will include it here.