enoughsaid05: 4) ...dxc4
Tal sacrificed the centre for greater piece mobility despite a more crammed space
To prevent Tal from setting up queen side formation with b5
Tal continued to set up pressure on the centre.
First he started with Bb4 to pin the knight on c3, followed by c5! (if dxc5, qxc5 will cause white to lose the castling privilege) and finally Nc6! with a threat of cxd4, winning a knight.
With this trap set up, white scrambles to protect his d pawn with Be3, cramming his own space.
Be3 is untimely, and is in a very unstable position. As we can see, 9) Ng4! threatens to send the bishop scrambling for life.
White is desperate to release the pressure. The knight on e4 however is causing white to lose a few tempo with f5!, h7!, e5!
From move 18, Tal is going to weaken the king side.
20) ... Ne3!!
This give Black a big plus in attack and tempo. If fxe3??, Black hits with 1) ... Bxh3 2) Bxh3 Rxf3 with a threat of Bc5, directing the fire power in the direction towards the king.
Black's game went downhill from there.