The first one plays the way everybody plays at first, on purpose.
Applies at once, mid-game.
The rules take thirty seconds. The one idea underneath them takes a game or two, and it is the opposite of what everybody assumes.
Place a disc so that it traps an unbroken line of your opponent's discs between the one you played and another of yours — in any direction, including diagonally. Everything trapped turns over. If you cannot trap anything, you have no move and your turn passes automatically. When neither side can move, whoever has more discs wins.
Every disc you own is a disc that can be turned back. A player who takes the biggest flip every turn builds a large fragile blob, runs out of safe moves, and hands over a corner. Through most of the game you want fewer discs than your opponent, in a tidy clump, with plenty of moves available.
There is no line through a corner with another square beyond it, so a disc in a corner can never be flipped — and neither can the discs it anchors along the edges. Corners are the only permanent thing on the board.
The diagonal neighbour of an empty corner (the "X-square") is the single most expensive square on the board — playing it usually hands over the corner within a move or two. The board here rings it in red when you have it as an option. Sometimes you have no choice. Know when that is.
You win Othello by leaving your opponent with nothing safe to play, so that they have to open a corner for you. That is why the engine here would rather have five good moves and twelve discs than thirty discs and one legal square.
Near the end the count stops being a proxy and starts being the result, and the position is small enough to work out exactly. The Sharp opponent stops guessing at that point and solves it — so if you are going to be ahead, be ahead before then.