What’s unusual about this position?

Twenty-eight consecutive checks:

1. c7+ N(8)xc7+ 2. bxc7+ Nxc7+ 3. dxc7+ Ke7+ 4. g8(=N)+ Rxg8+ 5. hxg8(=N)+ Qxg8+ 6. f8(=B)+ Qxf8+ 7. Qe8+ Qxe8+ 8. d8(=Q)+ Qxd8+ 9. c8(=N)+ Rxc8+ 10. bxc8(=N)+ Qxc8+ 11. Bb8+ Bxe4+ 12. Nd5+ Bxd5+ 13. Nc6+ Bxc6+ 14. Rb7+ Qxb7 mate

(Composed by Leathem.)