Ke1 → Qd4# mate: Traxler Counterattack line

White retreats the king toward home. Still not safe: checks drag it back out for mate.

1. e4
2. e5
3. Nf3
4. Nc6
5. Bc4
6. Nf6
7. Ng5
8. Bc5
9. Nxf7
10. Bxf2+
11. Kxf2
12. Nxe4+
13. Ke1
14. Qh4+
15. Ke2
16. Qf2+
17. Kd3
18. Nc5+
19. Kc3
20. Qd4#