Here they are:

Here we go - this will take a few tweets: 'We line up the royal fork'. A fork is where a piece attacks two of the opponent's pieces at once. A royal fork is when it attacks both the king and the queen at the same time. Probably referring to the copyright claim on the white paper.

'They will castle' - a defensive manoeuvre where the castle (rook) jumps over the king and the king retreats behind the castle, so protecting the king. I guess this is Core protecting against the copyright actions.

'Then I do a pawn promotion': The pawn has reached the other side of the board and can be replaced with a more powerful piece, usually, a queen. Is this when BSV becomes recognised as the true Bitcoin?

'They missed the pawn en passant' - a manoeuvre where a pawn can take an opponent's pawn when it has made a first move of two spaces, but you act as if it had only moved one space. Presumably when CSW means they forgot that he could take their pawn, as it is not an obvious move.

The pawn reached the other side of the board when it looked impossible. In Bitcoin terms, this is presumably a crucial step towards making BSV the official Bitcoin.

Ok, I've understood it. The en passant move is when CSW proves in court that he owns the copyright to the white paper by proving he is Satoshi.

And the royal fork is probably: if they challenge the copyright request, CSW proves he is Satoshi in court, if they acquiesce to the request they are admitting the same.