Series helpmates with twin by moving black king 2

a) 1.f1Z 2.Zd4 f8Z#

b) 1.f1N 2.Nh5 f8N#

A bit too short, but corresponding promotions. Extension to even more phases possible?

a) 1.Ke6(+f6) 2.Ke5(+e6) 3.Kd4(+e5) 4.Kc5(+d4) 5.Kd5(+c5) Gc6(+e4)#

b) 1.Kh6(+g6) 2.Kg5(+h6) 3.Kh4(+g5) 4.Kg4(+h4) 5.Kh5(+g4) Gh7(+e4)#

Minimalistic twin and of course, the bK has to move. He creates two sarcophagi for himself and White mates once by newly born pawn and once directly by grasshopper.

a) 1.g1nS 2.h1nQ 3.nQh7 4.nSf3 5.nSe5 nLOxe5-f5#

b) 1.g1nB 2.h1nR 3.nRh5 4.nBc5 5.Kb5 nRxc5#

Two neutral mates. Neutral pieces can be actively moved to guard squares around bK, but it is necessary to construct mates without possible reversals of the mating moves. Locust capture is the one of course, bur rook mate is more sophisticated.

a) 1.a1R 2.Rg1 3.b1GR 4.GRf3 5.GRh2 GRd3#

b) 1.a1B 2.b1GR 3.Bg7 4.GRf3 5.GRh7 GRe2#

Gnurider is able to mate from a long distance. Of course, with Alphabetic chess it is not necessary rem to take care about move order, it is easily given. So it is enough to take care about right promotions.

a) 1.Gg1 2.b5 3.b4 4.b3 5.b2 6.b1G 7.Ge1 8.Kf1 Qf3#

b) 1.Gf2 2.Gd4 3.Ke4 4.Kd5 5.Kc5 6.Gb6 7.Kb5 8.Ka6 Qa4#

c) 1.Gh6 2.b5 3.b4 4.b3 5.b2 6.b1R 7.Rb6 8.Rf6 Qg4#

Three phases, that is something! The mates and the strategy are however different in all of them, so there is still a large space for improvements.

a) 1.Kxd5 2.exd6(Gc4) 3.Kxc4(Gc5) 4.dxc5(Gb3) 5.Kd4(Gd5) 6.c4 7.cxb3 8.Kxe5(Gc4) 9.b2(Ge4) 10.b1R 11.Kxd5 12.Rf1(Gh5) 13.Rf4 14.Kxe4 Gxf4(Gh4)#

b) 1.exd6 2.Kb7(Gc5) 3.dxc5 4.Kc6(Gd4) 5.c4 6.c3 7.c2 8.c1Q 9.Qg1 10.Qg5 11.Kxd5 12.Qxe5(Gb5) 13.Ke4(Gf4) 14.Qxd4 Gxd4(Gb4)#

There seems to be about the right amount of analogy between two phases here. Different promotions and mirrored echo of the known specific Circe Parrain mate: bK cannot move up to thr 5th row or to the sides due to the rebirth of the black captured piece serving as a hurdle.

a) 1.Ke8 2.Kd7 3.Ge8 4.Kd8 5.Gc8 6.Ke8 7.Kf8 8.Gg8 9.Ke8 10.Kd7 11.Kc6 12.Kd5 13.Ke4 14.Kf3 15.Kg4 16.Kh5 17.Kh6 18.Kh7 19.Kh8 Kg6#

b) 1.Kh7 2.Kh6 3.Kh5 4.Kg4 5.Gh4 6.Kh5 7.Kh6 8.Gh7 9.Kh5 10.Kg4 11.Kf3 12.Ke4 13.Kd5 14.Kc6 15.Kd7 16.Ke8 17.Kf8 18.Kg8 19.Kh8 Kf7#

Again minimalistic change in twin, but with quite a big impact on the solution. Actually it is a bit of a bad luck that this constellation requires odd number of moves for Black, otherwise this could be in the form of two solutions. Very good for 4 pieces only.