If i have read it correctly there is no rating phase at the end of the jam. Is there any other way to recieve feedback? I think its kinda useless id you put hard work in a game, and when the jam is over nothing happends. Sure some people get number 1 and some number 500, but i think it is very usefull to get feedback, especially for new jammers. 

So, any idea on how to give feedback than? Since if there is no rating period its less likely that other players will play my game.

Hi Woomek! At the halfway and end points of the jam we threads + events held in the community for exchanging playtests and feedback with other members of the jam. You'll see them go up in a week both in the community and the Discord server, feel free to join them for some feedback on your game! Generally though this jam is not a competition--it's a community. A lot of the feedback and mentorship happens as the jam is taking place, not just at the end! We have a large focus on cultivating a welcoming community and allowing people to connect and ask questions of more experienced jammers along the way.