OMG Leaderboards is a simple backend for storing highscores for games and serving up leaderboards for specified timeframes (today, last 7 days, etc).

It was built with Unity3d games in mind, but is generic enough to work with any game capable of making an HTTP connection.

Cheaters are prevented from posting fake scores by a use of a shared secret (the salt) which is used to hash the game_id, score and player nickname sent to the server. Since this 'salt' is stored on the client side, you should obfusicate your game code somehow to try and prevent it's disclosure.

In a web browser, go to http://omgleaderboards.appspot.com/addsalt and enter a game_id and secret salt value.

Or, on the commandline use curl like:

curl --data "id=somegame&salt=mySecretKey" https://omgleaderboards.appspot.com/addsalt

curl --data "id=somegame&nickname=AwesomePlayer&score=1110&hash=6b959d6bf1f873a1c3c3f63f2d8a00ca" https://omgleaderboards.appspot.com/add

(or, including 'platform' and 'extra' fields)

curl --data "id=somegame&nickname=AwesomePlayer&score=1110&platform=android&extra=level:1&hash=9eb892ff26bd3471f59fbc4b2c353ea3" https://omgleaderboards.appspot.com/add

Obviously in your game you would make this POST request programatically however you want.

import hashlib
str_to_hash = game_id + str(score) + nickname + platform + extra + secret_salt
hash = hashlib.md5(str_to_hash).hexdigest()

(to do this in Unity, see http://wiki.unity3d.com/index.php?title=MD5 )

(specifying some timeframes and to return the top ten scores)

http://omgleaderboards.appspot.com/get/somegame?timeframes=today+last7days&limit=10

http://omgleaderboards.appspot.com/tasks/update_timeframe_tags

You will probably never need to use this, but it's useful to know that it will run in the background each hour.

So, you've decided you need to get your data out of OMG Leaderboards. Maybe you want to run some offline statistical analysis, maybe you are just moving to another leaderboard system and would like to import the existing scores.

Enable the Remote API in app.yaml (uncomment the 'builtins' stuff). Run appcfg.py update so this change is reflected in the production app. You may want to put the app into read-only mode while you do the export (depending on your requirements).

Edit tools/export_to_jsonlines.py to reflect your domain and App Engine SDK location.

Run: python export_to_jsonlines.py | tee scores.json

This will produce a file with one JSON object per line, for every Score entity in the datastore.

Note that the free quotas for Google App Engine datastore reads are quite limited and the charges beyond the free quota are comparatively high. It may end up costing you a few dollars with billing enabled if you wish to export more than ~20,000 scores in a single day.