A disgusting game

4... Bg4?? If knight takes knight that bishop hangs

7... Nb4 hanging the bishop for no reason

11... Be7 White's queen is hanging, but black does not take it

13... d5 is just ugly, I would play Bh4+

18... Bg5 misses bishop takes bishop then rook check to win a pawn

37... Kd6 weakened the black defense

38... Kc6 made things even worse

These are the most serious ones that make the position the worst that I can see

4. Nd5 Bg4??

should have been followed by

5. Nxf6+ Qxf6 or gxf6 either is followed by

6. Qxg4 thus winning a peice.

18. Bf2 should be followed by

18 ... Bxf2 19. Kxf2 Rd2+ thus winning material and giving black a chance to stack rooks on white's back row. Even if that fails black now has an excellent chance at softening White's queen side with a pawn storm to follow.

Black is at a clear disadvantage having a bishop to knight in a locked pawn end game. Black needs to open some lines but even in a locked position he has some fight left. Black's defense clearly crumbles after 33. Rxd4+ exd4. Offering that exchange was a terrible idea.

1) 9. ...Bh5 lets the bishop become a target

2) 27. ...Ba6.  Same bishop, haha.  You let it get locked in again.

3) 31. ...Rd4?  I'm not sure what you were trying to do with that move.  Better to start pushing your queen pawns and free the bishop, or get the king closer to the action.  Every single white pawn is on a white square - they'll make excellent targets if you can ever leave!

4) 32. ...Kd7  Definitely trade off the rooks on d1, forcing the white king to take away from the center.  This puts his king behind yours in the race.

5) 35. ...Kd6  Although it's usually good to move your king into the center, I think g5 is stronger here, threatening to activate your bishop.

6) 36. ...Ke5  The king is sort of useless over there for the moment.  g5 is still better.

7) 37. ...Kd6  I think you know what I will suggest here, haha.

8) 38. ...Kc6?  Clearly the action is going to start up on the kingside.  Why move your king the other way?  Taking the pawn is ugly, but it's better than losing all of your kingside pawns!

You are dead here, so there isn't much point in picking two more.  You played a very solid game until the endgame.  I think it's dead even until you failed to play g5 earlier.  That is your only real 'mistake' here, the one that cost the game.

Hope that helps.  Good luck!

7 = royal fork on c2

11 = the queen is protected by the g1 knight

4. Nd5 Bg4??

Qb3 makes a double threat on move 7

and on move 11 don't matter should still take that queen b/c bishop takes pawn while pinning the knight following move, and suppose he moves king to save knight then anothe pawn hangs giving the advantage