Add the karma bot to slack just as it work in Hipchat It use AWS S3 to store the points.
Create a new Slack application, and install it to your slack space. On the app seting choose to add a bot. You will need to enter in line 7 the bot token returned by slack
If you run the script on ec2, just add a role to allow access to the bucket of your choice (and add the bucket name line 16) or you can specify aws access token line 11 and 12
The script need to run all the time
You can use http://supervisord.org/configuration.html#program-x-section-example to run the script
You need to add the bot user to every room
@user++ or @user-- (You can add up to 5 + or -)
thing++ or thing-- (You can add up to 5 + or -)
!karma to see your karma
!karma top to see the classment