chess online

I really enjoyed this one. Definitely a memorable puzzle.
The idea first hit me to block the pawn with the rook on e6, supposedly forcing the knight to move away from defending, as it was the only legal option, but that didn't work.
The spectacular part of this puzzle, for me, is that if the pawn on e7 decides to capture on 1...exd6, then it can no longer block the a1-h8 diagonal against the queen.
Here are all move options:
1.Rd6
1...Nb7 2.Rd2 and 3.Ra2#
1...Nc6 2.Rd2 and 3.Ra2#
1...Nc4 2.Qxb3+ Kxb3 3.Rd3#
1...e6 2.Rd2 and 3.Ra2#
1...e5 2.Rd2 and 3.Ra2#
1...exd6 2.Qh8
2...b2 3.Qxb2#
else 3.Qa1#
I don't think I missed any, but if I did, please mention it! Thanks.

I got this right away, probably because I started with looking at 1...Nc4 and saw the idea of the queen sac (Qxb3+) followed by Rd3# if the rook were on the d-file. From there, it was easy to see 1. Rd6! exd6 2. Qh8, as it is the only access square to a1, and the diversion of the d-pawn prevents anything from blocking the queen's path.