21 ( +1 | -1 ) I've faced it......as White. A good line is 4.Bc4 Bh4+ 5.g3 fxg3 6. 0-0 gxh2+ 7.Kh1.Black is 3 pawns up,but will have to give them all back to avoid being mated fast.7...d5! 8.Bxd5 Nf6 9.Bxf7+,and Black has problems due to the f-file pin.
109 ( +1 | -1 ) Cunningham variationAccourding to theory the check is a waste of time for black if white has f1 available. it is mixed if the king has to go to e2 the debate is open. Since I don't see any games with this opening in your active file I will give you a few lines. 4. Bc4 (seems to be the best. see above) 4... Bc4 (black succuming to temptation note how it becomes a loss of time) 5. Kf1 (new move g3 is the older move that leads to sharp play but black is equal with accurate play) 5... d5 (the only way for black to fight for the initative) 6. Bxd5 (exd5 is playable and trasposes to a spassky-bronstein Leningrad 1960 game) 6... Nf6 a) 7. Nxh4!? Nxd5 8. exd5 Qxh4 9. Qe1+ (9. d4) with a favorable pawn structure for the ending b) 7. Nc3 0-0 8.d4!? (d3 is more solid) 8....Nxd5 9. Nxd5 f5 10. Nxh4 fxe 11. Qh5 Be6 12. Nxf4 Qxd4! with a good attacking chances for black (hence d3 is better) c) 7. Bb3 Bg4 8. d3 0-0 9. Qd2!? (9. Bxf4 Nxe4 9. Nc3 Nh5!) 9... Bxf3 10. gxf3 Nh5 11. Qg2! Nc6 12 Qg4 Qg5 13. Ng1 Qxg4 14. fxg4! with a good game for white. These are a few notes from the book winning with the king's gambit by Joe Gallagher. The one GM who will play 2. f4 in response to 1....e5 everytime! Few will challenge him in his knowledge in this opening.
14 ( +1 | -1 ) Actually,...Kasparov played 4....Bh4 in a thematic tournament against Short. I doubt he would play it if it was not a good reply. 4... g5, d6, Nc6, Nf6 and a few others are good replies.
16 ( +1 | -1 ) WellKasparov has been known to play 1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. b4, and 1. e4 e5 2. Nf3 Nc6 3. d4, among others, both of which are not considered particularly good, although he scores well with them :)
64 ( +1 | -1 ) Well, the Evans is no good in general because Black has enough defensive resources available to at least equalize, and in many cases, to obtain a slight positional edge. It's a more useful weapon for and against amateurs like myself who have poor defensive skill and are liable to hang on to the gambited pawn rather than try to return it favorably.
The Scotch is interesting; I'm not sure why it isn't played more often than it is. True, Black can almost always equalize, but the road to equality in many Scotch lines is tough and complicated, and the Scotch favors players who are inclined to do their homework before a tournament.