Ok so i see a lot of people wondering how this works and whole there was a post earlier describing it in a bit if detail, i have some advice for people who like giving feedback in hopes of boosting that rating.
Now I'm no expert but this is what I've noticed. It takes a few minutes after leaving a rating for that to count to the stats. Now, if you leave a comment as well that's what brings up smart rating. And I've noticed. The longer and more thought-out comments not only give more score, but also eventually get turned into more cool points that a "nice game bro"or "worst game -10/10"
If a game is good tell them why. What works well together, what stands out as their strongest point, how you approached the game, etc.
If the game is complete garbage, it's not. No game jam game is horrible. Some are really bad but theres a time limit. Cobstructive criticism, not abuse. Talk about "x item is missing, here's what i suggest" or "if you add this x you may not know about it'll boost quality for a small time investment". If you kniw the engine they are using give them tips on better ways to handle things like collision detection,etc.
Make the feedback useful. After all, it's what a game jam is all about. Learning. Maybe the kid just it of school made a bad game but that doesn't mean he's bad, just new. Maybe the expert made an awesome game but there's always something new to learn. And thinking about your feedback will also really help you improve as well. Next game you make your own words will be in the back of your head making sure you don't make the same mistake as that one other guy, or making sure you think of something that someone else did.
TLDR; write constructive and thought or feedback as well as ratings for more score! And to help people grow!