P.S. Since there's time, the rules can be changed;
I'd like to hear what the respected participants of the tournament think about this!
Changing the rules regularly isn't very good, but maybe we could just have a couple of categories: medium and impossible (or hard). Maybe even better: hard. As practice shows, playing on impossible depends on many factors, and not everyone will be able to adapt to it in a short period of time.
P.S. And we don't need a lot of certificates: after all, it's a competition.