4... c5! rybka agrees this is the best move, finding it only at a depth of 12 and beyond. The game slightly favors white +0.15@15.
5... f5. rybka likes Nf6 as it almost always does early in the opening. f5 scores nearly as well. It's interesting that rybka is trying to induce Nf6 e5? where dxe5 fxe5 Nfd7 strongly favors black. White's big center quickly becomes a target instead of a strength and the e pawn falls. white has a small advantage here +0.25@13.
6... Bxf5. best.
7... Nd7?! rybka is looking at interesting knight moves, bouncing between Na6 and Nh6! In fact, it wants to play both moves in its main line (+0.27@14). Our move scores a little worse +0.48@15. We were following a game plan laid out by a 2300+ player, but apparently he didn't understand the position well either! :)
Rybka's main line has Nh6 as a useful move in response to white's Bd3. Now we aren't forced to trade on d3. Rybka is maneuvering the Nb8-a6-c7 with the intention of playing e6. Notice that the e pawn is backward on a half-open file, and if we can trade it, we can try to put a knight on d4 to shield the backward d pawn.
Rybka's main line ends up being total craziness... Qa5+ Qd2! Qxd2+ Kxd2! and black is using their pressure along the long diagonal to prevent white from making more natural moves.
8... Qb6. Rybka likes Qa5+, which makes sense (Qa5+ Bd2? Qb6 is awkward for white, possibly forcing Bc1 losing a tempo). Our move scores only slightly worse +0.31@14.
9... Bxc3+! Rybka agrees, but only at a depth of 12+. White still has a solid advantage though +0.41@15. Our opponents are playing the opening very well.
10... Qa5. Just as good as rybka's preferred Ngf6.
11... Nb6. Just as good as rybka's Ngf6. We are closing the gap +0.17@14.
12... Bd7. Very close in value to rybka's Be4. We were pulling ideas from a master game and seem to be applying them very well. +0.29@14.
13... Na4. Another very small slip in value. Rybka still demands Nf6, and we slip from +0.28 to +0.40@15.
14... e6?? A huge blunder and we are getting crushed. Rybka wants Nf6 with white still holding a very small edge. After e6, rybka gives the main line as dxe6 Bxe6 Qe4 and things are so bad that black castles queenside rather then protect the bishop. +3.17@16! Wow, we got very lucky to draw from here!
15... hxg6. Best. White misses the best line but still has a crushing advantage. +2.60@14.
16... Kf8?? Drops a rook as white now has f5 exf5 Qxd6+ Ke8 Qe5+ winning the a8 rook.
17... exf5. Best, but hopeless if white plays correctly.
18... Ne7?? Scores much worse then Ke8, but Ke8 Qe5+ is completely crushing for white too. The game is now beyond any hope: +12.43@11.
19... Rd8?? Rybka announces mate in 6. Extra credit to anyone who can calculate this line.
20... Qc7?? White blunders badly, bringing the game back to +3.20@13. We blunder right back as Rxf5+ is still crushing for white, scoring over +6.0. Probably our move is best in practice as white has obviously missed the tactics with Rxf5. We took a chance that they would miss it again and they did.
21... Kg8. Best. White is completely crushing +6.15@13.
Here we wisely took a draw by repetition, as white has an easy win:
computer analysis and post-mortem of this game: http://www.chess.com/votechess/game.html?id=17905&ncc=1#first_new_comment
4... c5! rybka agrees this is the best move, finding it only at a depth of 12 and beyond. The game slightly favors white +0.15@15.
5... f5. rybka likes Nf6 as it almost always does early in the opening. f5 scores nearly as well. It's interesting that rybka is trying to induce Nf6 e5? where dxe5 fxe5 Nfd7 strongly favors black. White's big center quickly becomes a target instead of a strength and the e pawn falls. white has a small advantage here +0.25@13.
6... Bxf5. best.
7... Nd7?! rybka is looking at interesting knight moves, bouncing between Na6 and Nh6! In fact, it wants to play both moves in its main line (+0.27@14). Our move scores a little worse +0.48@15. We were following a game plan laid out by a 2300+ player, but apparently he didn't understand the position well either! :)
Rybka's main line has Nh6 as a useful move in response to white's Bd3. Now we aren't forced to trade on d3. Rybka is maneuvering the Nb8-a6-c7 with the intention of playing e6. Notice that the e pawn is backward on a half-open file, and if we can trade it, we can try to put a knight on d4 to shield the backward d pawn.
Rybka's main line ends up being total craziness... Qa5+ Qd2! Qxd2+ Kxd2! and black is using their pressure along the long diagonal to prevent white from making more natural moves.
8... Qb6. Rybka likes Qa5+, which makes sense (Qa5+ Bd2? Qb6 is awkward for white, possibly forcing Bc1 losing a tempo). Our move scores only slightly worse +0.31@14.
9... Bxc3+! Rybka agrees, but only at a depth of 12+. White still has a solid advantage though +0.41@15. Our opponents are playing the opening very well.
10... Qa5. Just as good as rybka's preferred Ngf6.
11... Nb6. Just as good as rybka's Ngf6. We are closing the gap +0.17@14.
12... Bd7. Very close in value to rybka's Be4. We were pulling ideas from a master game and seem to be applying them very well. +0.29@14.
13... Na4. Another very small slip in value. Rybka still demands Nf6, and we slip from +0.28 to +0.40@15.
14... e6?? A huge blunder and we are getting crushed. Rybka wants Nf6 with white still holding a very small edge. After e6, rybka gives the main line as dxe6 Bxe6 Qe4 and things are so bad that black castles queenside rather then protect the bishop. +3.17@16! Wow, we got very lucky to draw from here!
15... hxg6. Best. White misses the best line but still has a crushing advantage. +2.60@14.
16... Kf8?? Drops a rook as white now has f5 exf5 Qxd6+ Ke8 Qe5+ winning the a8 rook.
17... exf5. Best, but hopeless if white plays correctly.
18... Ne7?? Scores much worse then Ke8, but Ke8 Qe5+ is completely crushing for white too. The game is now beyond any hope: +12.43@11.
19... Rd8?? Rybka announces mate in 6. Extra credit to anyone who can calculate this line.
20... Qc7?? White blunders badly, bringing the game back to +3.20@13. We blunder right back as Rxf5+ is still crushing for white, scoring over +6.0. Probably our move is best in practice as white has obviously missed the tactics with Rxf5. We took a chance that they would miss it again and they did.
21... Kg8. Best. White is completely crushing +6.15@13.
Here we wisely took a draw by repetition, as white has an easy win: