This time I was close but couldn't see it to the end :)

whats the starting move?

:)

I think this position is too easy..
do you think the following variation is not the best for white??

1.Nb4+ Kd4 (forced if 1...Ke4 or 1...Kd2, 2.Rc4 and 2.Rc2 will end the game)

2.Nc2+ Kd5 (forced too if 2...Kd3 3.Be2+ Kd2 4.Na1 Rh2+ 5.Kf1 Re2 6.Rc2++- and if 2...Ke4 3.Bf3+ and then white can take the rook for free)

3.Ne3+ +-

(3...Kd4 or 3...Ke4 leads to mate 4.Rc4+ Kd3 5.Be2+ Kd2 6.Rc2 mate)
(3...Kd6 4.Nf5+ wins the rook )

If you feel that I've missed something, please point it out.. That will be useful for me.

1. Nb4+ Kd4 [1...Kd2 3. Rc2++] 2. Nc2+ Kd3 [2...Kd5 3. Ne3+ Ke4 (3...Kd6 4. Nf5+-; 3..Kd4 4. Rc4+ Kd3 5. Be2+ Kd2 6. Rc2++) 4. Rc4+- (same as 3...Kd4 variation)] 3. Be2+ Kd2 4. Na1 Rh2+ 5. Kf3!! [5. Kf1 Rh1+ and takes the a1-knight] 5...e4+ [only move] 6. Kg3 [the trick] Re2 7. Nb3+ Ke3 [7...Kd3 8. Nc1+ and the rook falls; and 7...Kd1/Ke1 8. Rc1++] 8. Rc3++. The trick is that had white played 5. Kg3 instead of 5. Kf3, then in the main variation, black could have escaped with ...Ke4 after Rc3+, so by 5. Kf3!!. white forced Black to push the pawn to e4 and block the king's escape route.

Nice composition!!