Here's an idea that came to me. Shouldn't we create a Player Rating for Tournaments? Find an algorithm that translates tournament successes into numbers and create a table.

Great idea.

we only consider HOMM3 online

What did club tournaments do wrong? They are the same qualifying tournaments that are currently running.

Participating in any tournament gives a certain basic number of points.

It shouldn't. Because it encourages point farming. Like, you sign up for all the tournaments, lose in the first round, and do the points still get added?

In my opinion, it's worth giving points starting from the quarterfinals (and even then, only in major tournaments), and not many, with the main bonus going to the winners.

Maybe it can only start counting from this year? Otherwise, the question arises of how far back to dig on other resources?

I think it's better to go back three years, with coefficients for the time elapsed.

For example, 0.97^N, where N is the number of months since the end of the tournament. Tournaments that are one year old will have a coefficient of 0.7, and tournaments that are three years old will have a coefficient of 0.33.

We divide tournaments by "weight" - importance.

I suggest the following formula:

Tournament weight (N) - the number of points the winner receives:
1) N=100 for top tournaments, which you qualify for through qualifying rounds (RP, PL, Best, future CIS championship),
2) N=75 for regular tournaments with a strong lineup (for example, seasonal cups, St. Petersburg championship, qualifying rounds for top tournaments, etc.),
3) N=50 for fan tournaments, various irregular tournaments, etc.

Points for performance are calculated as "tournament weight (N) * performance success coefficient (K)".

1. Winner, K=1

2. For round-robin tournaments like RP, K = 1 - 0.9 - 0.8 - 0.7 - 0.6 - 0.5 (exactly 6 places that retain their spot for the next season)

3. For cup tournaments with an Olympic system (or group stage + Olympic system)
K = 1 - 0.75 - 0.5 - 0.5 (that is, points are awarded starting from the semi-finals)