3. Qa8+! , of course, not 3.Bxc1 for the very simple reason, but the refusal of capturing the queen here is I think nice and elegant. And now study gets the introduction as the play does not begin directly with the thematic promotion to the various pieces.   

6. Qh1#  - mate from the corner!

2. Rxe1+    the thematic play arises:

2.  ...             g1=Q   leads to   

3. fxg8=B!   (3.fxg8=Q? stalemate)

3.fxg8=N? would be not good either: after 3. ... Kg2 4.Nxe7  h1=Q 5.Nf5 ( 5.Nd5 Kf2 6.e7 Kxe1 7.e8=Q+ Kd2 is also drawn) 5. ... Kf2 6.Re2+ Kxe2 7.Ng3+ Kf3 8.Nxh1 Bc5  it is a draw.

Again White chooses the same piece for promotion  as Black! 

Here 3.fxg8=B? is bad: 3. ... Kg2 4. Bh7 Kf2 5.Be4 ( 5.Rxg1 hxg1=Q 6.Bd4+ Kg2 7. Be4+ Kf1 8.Bxg1 Kxg1 9.Kxb3 Kf2 10.Kxb4 Ke3 11.Bh1 Kd4 and 12. ...Ke5 is also draw) 5. ... Kxe1 6.Kxb3 Ne2 7.Be5 Kf2 8.Bxh2 ( 8.Kxb4 Ng3 9.Bc6 h1=Q 10.Bxg3+ Kxg3 11.Bxh1 Kf4 12. Kc5 Ke5 ) Nd4+ 9.Kxb4 Nxe6 10.Kc4 Ng5 11.Bh1 Nf3 12.Bb8 e5 - and White is unable to win - 13.Ba7+ Nd4 14.Kd5 Kg1 15.Be4 h2 and 16. ...h1=Q   

If  4. ... Kf2 5.Nf5 Kxe1, then 6.Ng3 Ne2 7.Nh1 Nc3+ 8.Bxc3! bxc3 9. e7 b2 10.e8=Q+  Kd2 (10. ...Kf1 Qe3) 11.Qe4 Kc1 (11. ...c2 12.Qb4+ Kd1 13.Qxb2 c1=Q 14.Nf2+ )      12. Qf4+ Kc2 (12. ...Kd1 13.Qb4) 13.Qxh2+ Kb1 14.Ka3 c2 15.Qe2 c1=Q 16.Kb3 or 15. ...h2 16.Qe4

6. Rf1+! (very nice!) Kxf1

Or, if 5. ...       h2 ( instead of 5. ...Kf2), then

7. e8=Q!   The newly-born queen has just in time taken under control squares a8 and c6 from the checks of Black queen, and White wins.