activity is define (for now) by how many (ranked) matches you played in last 30 days. if you played 30 or more your activity is 100% if you played 15 your activity is 50% I hope you can compute the rest.
ELO = activity% * BaseElo
BaseElo start at 100000
I just had some trouble getting it to run.
When starting it,i would get the error "side-by-side configuration invalid"
To fix it I had to install the x86 version of this https://www.microsoft.com/en-us/download/details.aspx?id=26347
(if this doesnt fix it: the version you need is listed in Control Panel -> Event Log, there should be an entry for your error, in the details it shows what it is looking for (and cant find))
o'Clock liked a post in a topic by Kubik in (Question)ELO drops due to innactivity