Rating system for online games in Heroes of Might and Magic IV.

Hmm... it could be made even harsher, either by not dividing at all or by multiplying. It just took up an extra space in the table, and for that, it will be penalized by deducting points. The question is, how many...
Rnew=Rold-N/2 or Rnew=Rold-N or Rnew=Rold-N*k, where k is a coefficient.
What do you think?

Well, in my humble opinion, the coefficient "k" should be present... How about combining the first and third formulas, for example: Rnew=Rold-N/2*k? Although, of course, it could be simpler...
The participant should be more aware of what missing a match will cost him, or at least not make empty promises about definitely fighting...