An aggressive repertoire

Black can't only equalize against 2 f4. In the 2... exf4 3 Nf3 g5 black actually gets an advantage. Fritz says about -.6. As I went through the book moves, the assesment was similar. Therefore, Spassky won those games because he was spassky, which is quite a compliment to him. Black is supposed to have the advantage, yet spassky wins every time!

The book is quite good apparentely......

On it's face, "several hundred years of chess history" doesn't prove it is sound.

It's entirely possible that it is "unsound but playable OTB". Imagine what might happen in a top-level GM match, where one player always had to play the KG as white as their handicap. I don't know the answer as to what would happen, but I think some great lines would be prepared by Rybka and the rest of them. I imagine that white would be fighting for equality right away.

I guess "unsound" might be a tad strong, depending on the outcome of the computer analysis. The term implies that white is losing with best play. But if white is struggling to get equality even - one can at least call it "bad".

It's just that with the recent advent of computers being super-GM quality, especially in tactical games, I don't think that a couple hundred years of games really holds a candle.

1.e4 c6

Stonewall?

That too. Having alot of preparation for a sharp opening whether sound or unsound is extremely dangerous, but spassky was also a fine attacking player and pretty much good at everything. The problem with the KG is that it not only loses a pawn, but when black plays ...g5, he threatens things like ...g4 follwed by ...Qh4+ while white wants to play d4, but it isn't always possible. White has quite a loose position. Black does too, but his chances are simply better, and white is supposed to have the advantage, not black! I'm mostly fine with equality with white, but not worse with a loose position under pressure to try to get a pawn back.

   AnthonyCG is quite right.  The English opening is not what one would call aggressive either, but of course you are looking for a change.  Also don't think the King's Indian Attack is right for new players.

   I am almost on the same page with Hicetnunc.

(WHITE) (KP) Danish Gambit, Smith-Mora Gambit, (QP) Trompowski Attack and Torre Attack. 

(BLACK) Two Knights' Defense, Falkbeer Counter Gambit, and Open Ruy Lopez. (BLACK) Albin Counter Gambit and Englund Gambit, Budapest Defense.

What about the stonewall, or the Queen's Gambit? Two I've never played

Spassky beat Bobby Fischer with the King's Gambit...at least twice.  This inspired the Fischer defense, ie. 1.e4, e5 2.f4, exf4 3.Nf3, d6 4.d4, g5 and so on....  This doesn't prove the King's Gambit is sound, but it does show that the King's Gambit can be a nice weapon, at least a suprise weapon.  If it were played more often, then....

 Spassky and Fischer played only one kings gambit, which Spassky won.

Part of the problem is that the "best" White weapons become the most heavily analyzed and therefore often lose their punch.  KG is as good as anything if a draw=a loss.

Give the Alekhine's Defense a try. It is aggressive, leads to sharp play, and isn't very popular, so some people don't know how to play against it.

This is exactly how opening theory develops - one master game shows one way of playing it, black then finds a better way, white counters that, etc. When we are blessed with a Kasparov - Karpov match which investigates certain openings deeply, over and over, this has the effect of compressing years worth of opening development and analysis into a single match. I would contend that an opening which is "sound" must be able to withstand such odds. If it does not, then it is not sound.

Of course you don't put Kramnik playing the white pieces of a KG against Topalov, haha.

If you _really_ wanted to put your money where your mouth is, you would take the Shabalov approach. Play a double round robin tournament including all the top engines, let them duke it out. See what types of positions develop. Of course this is not my idea but I read about it in a Shabalov article in CL. This is the type of analysis which would be done by the GMs before our hypothetical match, but it would only be their starting point.

1.e4 c6

I disagree with your characterization of the problem. It's been written that Kramnik has the narrowest opening repertoire of any world champion, and yet he knows these openings better (typically) than his opponents do. Yes, if the opponent KNEW that he would be facing a King's Gambit (Royal Gambit, in Russian), then white would lose the surprise factor. But - this exact factor should not be and is not relevant in determining whether the opening is suspect or unsound. I completely stand by my statements above.

I should note that I know nothing about the King's Gambit, I never play e4, and if I did, and if my opponent playe e5, I wouldn't even consider f4. But the approach to all unsound openings should be the same. If you substitute out King's Gambit and instead put in Smith-Morra Gambit, then I would say pretty much the same stuff. I'm not saying that the openings are refuted, but in the line between suspect -- unsound -- refuted, I would begin the analysis process by thinking it would end up closest to unsound, leaning towards refuted.

I admire your never ending quest to refute my opening though!

1.e4 c6

Not necessarily, because those opponents have to prepare for a different player every day, while the player who always plays the same opening becomes a complete specialist in it.

Anand is a 1.e4 specialist who knew beforehand that Kramnik only played two defences to 1.e4 - the Berlin and the Petroff. So what did he do for the match? Switch to 1.d4 for the first time in his carreer...

The petrov is sound because black has a perfectly solid position. The king's gambit is suspect because black can find ways to get an advantage. If white has a slight advantage in a certain line of the petrov, that's fine but white is taking some pretty big risks in the king's gambit. This is all theoretical though, I think black gets the advantage, but I in no way would ever disrespect a player who used it against me as it can be so loose and I know not enough theory of it. But as level increases, it becomes more important to play sound moves, although I think lower levels don't necessarily justify playing an opening like the KG just to try for a win. Anyways, I play 1...e6 so I won't ever face it. Any alternative to that move could possibly be 1...c5, but not ...e5. I think the Ruy has great chances to win. He wins much more than black, even though there are draws and there is tons of room to outplay the opponent.

I have read that Spassky never lost from the white side of the kings gambit. I do not know if this is true or not but if it is this is truly amazing ! Perhaps some of you young fellers might look this up to see if its true or not? I am too lazy to do so myself.

It really is incredible.

 Thanks for doing that gonnosuke ! I can now say its true and am in even more awe of Spassky than ever.....

GM David Bronstein scored 73.5% with the King's Gambit (+21 =8 -5).  GM Joe Gallagher scored 73.4% with the KG (+49 =18 -12). I guess that that is because they are Bronstein and Gallagher.

I am impressed by these numbers.

But to correct the previous post, GM Bronstein did not win 73.5 of his games. He scored 73.5% from the white side. Likewise for GM Gallagher.