Greetings, dear colleges.
My name is Kirill.
I ve been working in the gamedev for 1 year

I have several concepts of my own and heard about the young developers support.
How to make game with gamesas?
(Not How to sell the idea?)

Is Playable demo necessary or GDD and concepts are enough?
Thabnk You.

We're not accepting concepts, unfortunately. A finished or nearly finished game is required.

may I ask why gamesas is not accepting game me concepts because the community is the greatest source also how do you expect young aspiring gamesdev/students to make them self known in the industry

Because we already have way more concepts than we need. Concepts, while individually difficult or challenging to create, don't take nearly as much time and energy to create as a finished, polished game. A concept is only one small piece to final game and it takes a long time and lots of people to go from concept to game.

We don't have the resources to produce every concept that we've created internally, let alone all the concepts from outside game designers.

That's the reason. Hope that helps.