The title feels misleading. I don't think this is what people would think of when they hear the word "multiplayer". So on top of being just regular chess, to play it you need a second person who for whatever reason would want to play chess with you in a single shared computer instead of using good old physical pieces. Meaning nobody.
Also fullscreen should be an option, not a necessity.

Queen goes on her own color. Its impossible to implement the 4 move checkmate with both queens on the black square. Switch the white queen to the white square.

why are you named it 3D chess if it`s regular 2d???

honestly this game is fun although it dosn't meet some people rating, i like it

The chess rules are poorly implemented. For instance, you can move yourself into check which is not allowed. Pawns does not promote and you cannot castle. With this in mind, I was actually surprised that you implemented the en passant rule, but I saw later that that was because someone commented on it. When implementing a game like chess, study the rules first.

Game looks ok, but it's not interesting from another perspective than as a school project. There's really no point of playing this game. As have already been mentioned in other reviews, there are tons of chess games out there that actually get the rules right and offer a computer opponent. If I want to play with a friend, I would either use a game where we can use separate computers or just bring out a physical chess board.

One thing you can improve is to make the buttons for main menu and rules not overlapping the black rooks. That's just plain annoying.

It could have been something if you added some twist to it, like special rules (forgetting to implement original rules does not count) or if there were some nice animations or something. For examples of the latter, have a look at Battle chess for Amiga or one of the later incarnations.

And please stop with guilt trips. I saw your response "you need confidence and getting 2 stars just because there are millions of chess game and you did not click arrow to get it fit is shaking confidence" in another review. That's just bad style. You get the stars for what you have done, and not for what you maybe will do in the future. To make it even worse, that guy even praised your skills. Isn't that enough?

Also. please don't write the instructions in all capital letters. It's harder to read and is interpreted as shouting.