Regarding the coin puzzle and reply #97544. Good effort, but I believe a8 and h1 share a common diagonal…
|*|0|0|0|0|0|0|0| 8
|0|0|*|0|0|0|0|0| 7
|0|0|0|0|*|0|0|0| 6
|0|0|0|0|0|0|*|0| 5
|0|*|0|0|0|0|0|0| 4
|0|0|0|*|0|0|0|0| 3
|0|0|0|0|0|*|0|0| 2
|0|0|0|0|0|0|0|*| 1
_a_b_c_d_e_f_g_h_