We think 20 would be good amount of ratings, just like LD :) ! Not 100 percent sure yet though.
not sure how the system works with putting games on top. what I remember from previous game jams is I just played the first game, top left. Knowing that after rating a game and going back to the page there would be another game listed first. I can imagine a lot of people would rate like that, only look at the first 20-30 games on the list. But now that I think about it, if this would be setup as most played game first than it would be a bit unfair, especially with +1000 games.
The voting will never be fully fair because only a fraction of players will play your game. You can get lucky and have people play your game who like it and you get good ratings or you get players who don't like your game (or the game is too hard for them) and you get bad ratings.
Next question is, how fair are the ratings from others. Some could give low ratings to other games to boost their game. But I hope that the ratings will be looked through if there are some weird ratings or maybe cheaters, because this time you are able to win a price.
The problem with itch.io is that we have absolutely no control over rating so we can't do stuff like that. Also games are shown in random order every time you refresh the page.
We expect people to be fair when rating games, and in other jams we hosted we didn't really have problems with this (apart from games with very little ratings, but that should be solved now, kind of).