Implement a leaderboard

[robertmarsal]

It is nice to see one's high score, but it would be better to be able to compare with others

[gabrielecirulli]

Hi! I don't think this can be done in the current state of things. It'd require a big amount of work to implement a server to store the scores, which is a thing I'm not prepared to do at this point. Right now, the main vehicle for score sharing is twitter and it seems to be doing a good job so far

[Delapouite]

@robertboloc Hi. How could score forgery be avoided?

[robertmarsal]

I understand. I haven't really thought about the implementation of this feature.
@Delapouite I am no expert, but I don't think anything can be done to provide a 100% viable solution given that the client runs the code.

[slopjong]

@robertboloc can you beat me?

[robertmarsal]

😄 right now my best score is near 5000 points so, not yet, but with all the time I spend playing this game maybe I will... 😉

[Yogu]

I thought about preventing forgery a bit and this is what I came up with:

If you want to prevent the client from "undoing" an action, the client must send its move to the server, which then responds with the "random" tile added. This significantly decreases performance, especially for users with high ping. I think we'd have to live with the possibility of clients with an undo feature, if they exist.

But if you don't care about undoing, the following concept should work:

• The server has a rsa keypair
• Before the game starts, the server generates a bunch of random seeds and signs them together with a timestamp
• The client now uses one of these seeds to initialize the random number generator for addRandomTile
• The client records each move (this results e.g in Top-Left-Left-Right.... Invalid moves are not included.
• When the game is over and the user decides to submit the score, the client sends the signed seed, the move sequence and the score to the server
• The server now validates the signature of the seed, checks if it's not too old and not already used, and then simulates the game using the move squence. If everything seems ok and the scores match, it is accepted.

If you can share the game mechanics between server and client (with node.js), it shouldn't be that hard to implement. To reduce the server load, you could only accept scores that will be within the top 100 if accepted.

[slopjong]

@gabrielecirulli I love 2k :-)

5th game = 2nd win & new best score

[gabrielecirulli]

@Yogu thanks for the ideas but I'm not willing to personally withstand the server hosting costs and the development time for this feature.

[aks0]

@gabrielecirulli Awesome game! :)

[slopjong]

@aks0 Damn. You passed me, good job 👍

[gabrielecirulli]

Sorry guys, gotta close this. Nice scores, though. 👍

[charliezhang]

@Yogu Interesting thoughts on anti-forgery. One problem though, is that as long as the client decodes the random number generator it can predict the next game state deterministically. Then the search problem becomes significantly easier once you know what and where the next tile is, it is not a alpha-beta search anymore.

[charliezhang]

@Yogu BTW, here is an implementation of global leader board: http://go2048.com/rank.html

[Yogu]

@charliezhang That's what I meant with

I think we'd have to live with the possibility of clients with an undo feature, if they exist.

because otherwise, the game would be really slow (contacting the server for each move).

Thanks for the leaderboard link, got 29th :-)