https://qposts.online/post/365

Barnes Opening

https://en.wikibooks.org/wiki/Chess_Opening_Theory/1._f3

"Quite a rarely played passive starting move that gives up White's first move advantage. White's position is slightly weakened by the White King exposure to a check on the h4 - e1 diagonal. The Kingside Knight's favourite developing square f3, is also not currently possible. In fact, this is arguably the worst possible first move by White. It controls e4, but e4 could have been played right away.

This move is usually a way for the white player to taunt black, especially if his rating is much higher, basically giving black an edge straight away. In this fashion, white is oftentimes seen playing 2.Kf2.

Black's best move is to take advantage of the potential White King exposure to a check on the h4 - e1 diagonal. So the best move is:

1... e5. This very strong move takes advantage of the newly created weaknesses along the diagonal while controlling the center. Black is already better. It can also lead to the fools mate after 2. g4?? Qh4#. If Black replies with the slightly inferior 1... d5, play could go into a reverse Dutch defence. Another possibility for White is to transpose into a Blackmar-Diemer Gambit: 1. f3 d5 2. e4 dxe4 3. Nc3."

Blackmar-Diemer Gambit

https://en.wikibooks.org/wiki/Chess_Opening_Theory/1._d4/1...d5/2._e4/2...dxe4

"White has given up his king's pawn, in hopes of an aggressive game. Since there is no way White can win a pawn back immediately, he can expect this set-up most times he plays the Blackmar-Diemar Gambit. The best move for White would be Nc3, putting pressure on the e4-pawn and preparing the move f3, as 3. f3 is well met by 3...e5!, with an edge for Black. One example: 4. dxe5 (other moves are even worse, for example 4. fxe4 Qh4+ and Qxe4 with an extra pawn and an attack, or d5 Nf6 c4 c6 when d5 will soon fall) Qxd1+ Kxd1 Nc6 fxe4 (f4 Bg4+ Ne2 O-O-O+ with a winning attack) Nxe5 with an obvious advantage. Black normally plays 3...Nf6, though 3...f5 and 3...Bf5 are interesting ways to avoid mainline theory. Now, if f3 e5?, dxe5 gains a tempo on the knight. Sometimes Bc4 is played, to hopefully trap Black quickly with a variation of Scholar's Mate."

Parham Attack/Scholar's Mate

https://en.wikibooks.org/wiki/Chess_Opening_Theory/1._e4/1...e5/2._Qh5/2...Nc6/3._Bc4/3...Nf6/4._Qxf7

"With this move White gives checkmate. The Black King cannot take the White queen because the White Bishop on c4 defends it. Further, moving the Black King to e7(Ke7) does not allow it to escape capture on the next move, so this position is checkmate, and White has won the game."