Hey @Tuanyan. This is a club related to the 4 Player Chess and 8 Player Chess, originally created by @Automaton_Dragon. It features his version of a 16-player variant, which can be clearly seen here: https://www.chess.com/clubs/forum/view/16-player-chess-1. Unfortunately, the superadmin is not active in this club because he's busy.
No. I counted the 32x32 "box" in the main board, and 32x3 four times for extra rows or columns. 32 * 32 + (32 * 3) * 4 = 1,024 + 96 * 4 = 1,024 + 384 = 1,408 squares (not 1,280 or 1,900).