Level 9 is possible in a lot of positions it says it's impossible in. For example:
1. Nc3 Nc6 2. Nf3 Na5 3. Ne4 Nc4 4. Nd4 Nb6 5. Nc3 Na4 6. Nb1 Nc5 7. Nf5 Na4 8. Nd6+
the knight is missing on B1 but what did was missing in g1
