| a | b | c | d | e | f | g | h | ||
| 8 |  |  |  |  |  | | | | 8 |
| 7 |  | | | |  | | | | 7 |
| 6 | | | | | | | | | 6 |
| 5 | | | | | | | | | 5 |
| 4 | | | | |  | | | | 4 |
| 3 | | | | | |  | | | 3 |
| 2 | | | | | | | | | 2 |
| 1 |  | |  |  |  | | | | 1 |
| a | b | c | d | e | f | g | h |
King's Knight Opening
The King's Knight Opening is by far the most common response to the Open Game. It is characterised by the moves:
- e4 e5
- Nf3
It compromises ECO codes C40-C99.
ECO Codes[]
ECO Code C40 contains all irregular Open Games. Specifically, it includes every response from black apart from:
- Main line, 2... Nc6 (C44-99)
- Philidor Defense, 2... d6 (C41)
- Petrov's Defense, 2... Nf6 (C42-43)
The noteworthy openings in C40 are:
- Damiano Defense (2... d6)
- Elephant Gambit (2... d5)
- Latvian Gambit (2... f5)
- Gunderam Defense (2... Qe7)
- Greco Defense (2... Qf6)
For a list of all other ECO Codes, see List of chess openings.