1. Bf6 Kd6 2. Be7+ Kc6 3. f6 h2 4. Bf8 h1=Q 5. Bh6*
The queen cannot deliver a check from a8, and the white king comes to g7 safely. White has successfully built an impregnable fortress.
Analysis by Stockfish 170615 64 BMI2:
-+ (-6.70) Depth: 90/96 00:00:21 353MN, tb=2627521
Don't the engine understand that that white has barricaded himself in an unbreakable fortress

[fen]8/kp4K1/1N6/1P6/8/6N1/1p6/8 w - - 0 0[/fen]
Imprisoned King
1. Nd5 b1=Q 2. b6+ Kb8 3. Nh5 Qb5 4. Nhf6 * Komodo 9.02 -+ (-2.05) Depth: 43 00:00:12 468MN, tb=5990679
1. Nd5 b1=Q 2. b6+ Ka6 3. Ne2 Qa1 4. Nec3 * Komodo 9.02 -+ (-2.21) Depth: 39 00:00:08 312MN, tb=18545296
[fen]4k3/5ppp/8/8/8/8/PPP5/3K4 w - - 0 1[/fen]
Szén Position
Analysis by Komodo 9.1 64-bit:
+- (250.00) Depth: 41 00:02:39 3969MN, tb=114776563