In game two, like in game one, Topalov again found some excellent, very creative attacking moves but later played several inaccuracies and lost. So it is Kramnik two, Topalov nil.
What should Topalov do in game three? Should he play very risky attacking chess, and try the Benoni, Volga gambit, or King's Indian? I think rather not. Kramnik has shown time and time again that he is able to punish any opponent who dares to play these openings against him. Don't forget that Kasparov abandoned the King's Indian (and the Grünfeld) not the least because of his problems with these openings against Kramnik. If Topalov plays too risky with Black and loses game three... I think Topalov should play solid, and try to attack in game 4 with White. If he gets one win with White in game 4 or game 6 and does not lose game 3 nor game 5 with Black, he will still have all the chances in the match.
I think Kramnik will be happy with game one - not only with the result, of course, but also with the opening. He was prepared for Topalov's novelty 12..Ba6 and got exactly the queenless, technical position that he excels in. Kudos to Topalov for finding an excellent resource later in the game, when he was even able to press hard for a win. But I think the middle game was just very slightly better for White, and I am sure that Kramnik would not mind playing exactly the same line again and come up with an improvement somewhere. For example, Malcolm Pein suggested 19.Nbc4. Therefore I think Kramnik will play 1.d4 in game three again.
Topalov could go for another Catalan and play a different line. There are certainly many of them. Topalov has played the line 1.d4 Nf6 2.c4 e6 3.Nf3 d5 4.g3 Bb4+ 5.Bd2 Be7 6.Bg2 O-O 7.O-O c6 8.Bf4 b6 several times, but it is rather passive, and he lost his last two games in this line against Ponomariov and Kramnik. Maybe he could try the line 4..Be7 5.Bg2 O-O 6.O-O dxc4 7.Qc2 a6 8.Qxc4 b5 9.Qc2 Bb7 that Kramnik played himself against Kasparov in the last game of their world championship, and which Topalov's second Onischuk used last year to draw against Gelfand.
So what do I think will they play in the third game?
I think Kramnik will play 1.d4 again, but Topalov will switch to the Slav.